After a hard-fought legal victory, the anonymous OP ("a.k.a. the Original Poster") turned to Reddit's infamous AITA ("Am I the A--hole") forum to find out if he should be celebrating his win -- or if he was a jerk for even fighting in the first place.

While he certainly got a lot of support in the comments -- where he was extremely active engaging with Redditors -- it wasn't all love and support. In fact, some tore into him harder than his ex and her new husband probably ever thought about doing!

Read on to find out his story and the surprising reaction from some in the comments!

The 24-year-old man shared that he and his 28-year-old ex share a five-month old son, after dating for just eight months. "She left me for her ex and didn't tell me she was pregnant," OP added. "It was her sister who told me and she told me the baby was mine and my ex knew about it."

Once he became aware that he was to become a father, OP writes, "I reached out and told her I wanted to be a parent to my kid. She retaliated by marrying her ex and they told me he was going to be the father."

OP then promised to "file with the courts when the baby was born to establish DNA and custody." He said that when the baby was born, "they did everything to keep me away including adding her husband to the birth certificate and giving the kid his last name, which at the time of his birth was just the husband's name."

He went on to explain, "My ex changed hers last month before our court date." That's right. OP followed through on his promise to take this whole situation to court.

"DNA proved I was the father," wrote OP, adding that court-mandated mediation and therapy did nothing. "She was clear she wanted me out of the picture and wanted her husband to raise my son as his own," he explained. "The judge did not take kindly to that."

In his filing, OP also requested his son have his name instead of his stepfather's. "The outcome from court was 50/50 physical and legal custody. My son's last name was changed (as was his first name because my ex's husband was bitter he didn't get his junior in my son)."

Additionally, "We are to communicate through an app about our son and nothing else. Neither of us pays child support. We both have to make decisions for him. I'm also on the birth certificate now."

While OP got what he wanted out of the situation, the aftermath has been relentless enough that he turned to Reddit. "My ex hates me for all that I did but the sorest point seems to be the last name," he wrote.

He went on to note that her mom -- who he'd only met twice -- called "and told me I was a petty little kid who was playing daddy when her grandson deserved a real man for a father and he had/has one in the husband and I should have left them to raise him together so he could have the stability of one home."

She went on to say that for OP to "deny 'that wonderful man' the right to pass his name onto a child he swore to love as his own is awful and that my ex as the mom should share a name with her child."

Later, a friend of his ex confronted him "and she called me petty for fighting for my son's last name." At his latest custody exchange, the ex brought it up, too: "She told me she hoped I was damn proud of myself for fighting over the name when she had her husband's name too and she wanted it to be their family name and I denied their son that (she said their son)."

And so, he wants to know "AITA for fighting for my son to have my last name instead of his mom and her husband's?"

Despite OP detailing absolutely zero people siding with him in his story at first -- doesn't mean they're not there, just that he didn't mention anyone -- Reddit had his back in huge numbers, with many expressing shock and outrage at everyone involved with his ex.

"Why would you be any less deserving of fatherhood than your ex's husband?" asked one commenter, who scored 2K upvotes. "You fought against multiple obstacles to make sure you can be there for your son. And why should a man who is unrelated have your kid be given his name?"

To this, OP explained that her family believes her husband is "more deserving" because he's older, 30, and "he's got a pretty good job from what I heard in court (they used it as an argument against me)."

He said that his ex and her husband also argued that they can offer "a two parent household and a normal nuclear family without divorce or co-parenting involved, which they think is better." In another comment, OP conceded, "It's not exactly my dream either but it's my reality and I wasn't going to walk away from my son over it."

OP then offered a slight defense to her friends and family, adding, "I think they also just know him really well so they think he's this great person and I'm just this random guy my ex dated." He also shared that "her sister is being cool about it all though."

Some commenters warned OP that this fight was far from over an that his ex and her husband are "going to alienate him from you. He's going to call that guy as dad too. You need to be prepared for the parental alienation scheme for the next several years." They then urged professionals ("therapists and what not") to help navigate it all. OP agreed and said he "was warned" about this.

As he's witnessed kids with absentee fathers and strained relationships between parents, OP also assured Redditors he wouldn't bring drama with his ex into his child's world. "I wouldn't do that to my son. I'll make sure to do all my venting away from my son and to make sure he can never hear any of it," he promised. "I'll also try to see more positives about her so I can be civil for my son's sake. It's going to be the hardest thing but he's worth it."

All in all, OP was extremely active in the comments of this post, commenting more than 60 times as of this writing. While most of Reddit seemed to have support and sympathy for OP's situation, there were some who weren't so positive -- and some who were outrageously negative!

One person gave him an NTA, but also gave the story an ESH ("Everyone Sucks Here") before explaining, "She sucks bc hiding his true parental lineage is so problematic esp when it comes to health risks etc" and then asked OP why he wants to be involved.

"I get that he's biologically yours, but socially why do you want custody? Your post hasnt said anything about why you care. To spite your ex? Why do you want to raise a child in a toxic environment?" they asked. "He's gonna have so many issues growing up in such a toxic situation and I pray for him."

"Because he's my child. He deserves to know he was loved and wanted by me even if the circumstances aren't ideal," OP replied, saying he knows of so many kids who feel abandoned or unwanted because a biological parent didn't want to be in their life.

Despite the commenter continuing to argue that it's going to suck for the kid regardless, OP pushed back, "Knowing me is the least f--ked. Having his dad in his life I fully believe is the lesser damaging road. The judge agreed heavily too."

Still there were a few who absolutely went in on OP, with one flat-out calling him selfish.

"Wow how f--ked up can YOU be? If you don't understand how incredibly selfish you are being in this situation, you are really not fit to be a parent. At all," they wrote. "Do you seriously do not understand the stress you will put that kid through if he had a name different from the rest of the family? The bullying that will happen to him? Do you really have NO CLUE how what the effect on that kid will be????"

"I'm my son's parent too, not just my ex. My son deserves to know the truth," wrote OP. "He deserves to know he is loved. He deserves to know where he comes from biologically. He does not deserve to grow up feeling rejected or to feel rejected when he finds out the truth as many kids do."

When he asked how any of this is him being selfish, another commenter jumped to his defense, writing, "You're not. It's mental gymnastics by people projecting their own issues."

One completely unhinged comment started, "Your ex sucks for not aborting this child, who is going to start off his life with the stress of being ferried back and forth between different homes and having a stressed-out mother." They then trashed the sister for telling OP "and making this child's life more difficult."

Finally, the anonymous Redditor went in on OP, adding, "You suck for forcing your way into the life of a child that has two adults that apparently want it and care for it, despite your only contribution being a small amount of sperm."

"It's fairly clear that this is about your ego, (especially with the last name situation), or about keeping control over your ex who didn't want you in her life," they continued. "If you actually cared about your son's well-being and wanted to be a good father, you'd go ejaculate into someone else and let this child be."

This back-and-forth went on and got even more disturbing ("OP's forcing himself into his ex's life solely by virtue of sharing DNA because he wants HIS child" and "The child is a possession that's he's not willing to let go, despite him only being a biologically-related stranger") until another Redditor jumped in to ask the original commenter, "What the actual f--k is wrong with you?" Another agreed, adding, "Your take is bloody psycho."

There were some who went down a conspiracy theory rabbit hole that maybe the husband is infertile and this whole thing was an elaborate scheme pulled on OP. After all, the current husband and his wife were "exes" when she dated OP for eight months. And then when she got pregnant, OP was dumped without even telling him she was carrying his child, and now she and her ex-turned-husband are fighting to remove him completely from the narrative. Was he used just to impregnate her and he screwed up the plan by finding out?

"Well I guess that will teach your ex to steal sperm instead of paying for a donation at the fertility clinic like most other infertile couples do. I am sorry that you were coerced into reproducing for their benefit," wrote one Redditor. "I hope that you make as much effort in being a great father as you did to be recognized as a father. If so, I am sure that you will do a great job."

To this, OP promised, "I'm going to do my absolute best to be the dad my son deserves and to give him the life, the love and the security that he deserves."

"Don't let them drive you off. Be there to love your son, teach him to be a good person, and care for him. You are not just a random guy. You are his father," argued one Redditor, while another encouraged him to "ignore them all..... Be the best dad ever and continue to fight for your son."

What do you think?