'The Hills' Recap: How Brody Jenner Really Feels About Caitlyn Jenner Bailing On His Wedding
Inside the Premiere for 'The Hills: New Beginnings"

Brody and his mom reveal how long they knew about Caitlyn's transition, before he says it was "a bummer" she didn't attend his wedding.

Brody Jenner is still disappointed one family member didn't make it to his wedding: dad Caitlyn Jenner.

On Monday's episode of "The Hills: New Beginnings," Brody and his mother, Linda Thompson, detailed their relationships with Caitlyn, spoke about her transition and how she was a bit of an absent parent.

"My dad and my mom split up when I was around 2 years old. My dad and I never really had a great relationship," Brody revealed in a confessional. "Through all the ups and downs my family has had, my mom is definitely the rock. She's just a truly truly incredible person."

During a family dinner with Brody, his wife Kaitlynn Carter, brother Brandon Jenner and mom Linda, Thompson opened up about her marriage to Caitlyn, referring to her as "Bruce" in the past tense.

"I was so happily married to Bruce Jenner," she recalled. "I had this great normal life in this little house in Malibu until that fateful day standing right over there where Bruce said to me, 'I want to transition.'"

"My life just did a 180," Thompson continued. "In my mind, I had lost my normal, my family, my wonderful husband that I thought would be forever. I just lost my marriage and the father of my kids, I was devastated. But that was just a momentary reaction. My greater sympathy had to go out to Caitlyn."

Speaking to the camera, Brody said that his mother has known about Caitlyn's desire to transition "for decades." According to Jenner, Thompson "never told me until I was 27 years old."

"The way she handled that situation and waited to tell us until we were old enough to understand better was, I think, the right thing to do," he added.

Despite what Caitlyn was going through, Thompson said she doesn't give her "a pass for not being a father."

"I don't think there's any excuse ever to not be there for your children," she continued. "It's not something you would ever do, to have a child and not call them on their birthday or be a parent to them."

Of course, among those moments she's missed was Brody's June 2018 wedding to Kaitlynn in Indonesia.

"Right before our wedding, Brody's dad canceled on coming to the wedding, like a week before," Kaitlyn claimed. "Brody really just kind of brushed it off, but he has to have felt something, but he doesn't express it."

"Not having my dad at the wedding, it was a bummer," Brody admitted in a confessional. "Honestly, it really did hurt. I would have loved to have had her there but, she had better things to do [laughs], apparently."

So, what did Caitlyn do instead? Attend the Life Ball in Vienna, an annual event which raises money in the fight against HIV/AIDS.

Though Linda said her sons had ever right to feel "angry" and "slighted" by Caitlyn, she did feel her past mistakes were all still "forgivable."

"I'm not excusing Caitlyn, I'm just saying it's forgivable," she told her boys. "Everything in life is forgivable, and it's not even for the other person, it's for yourself. You have to forgive, so it doesn't eat away inside you."

"The Hills: New Beginnings" airs Mondays on MTV.