Read on to see how she responded to all the shade.
During the reunion, Dorinda Medley told Andy that "Luann didn't go to rehab because she had some huge revelation -- she went to rehab because she needed to stay out of jail and was practically court ordered."
"I was not court ordered to go to rehab," Lu clarified. "I went on my own recognizance, first of all, so Dorinda doesn't know anything about me. I went because I felt that I needed to go and take care of myself. I take it very seriously -- my sobriety -- and it's 51 days today, by the way."
Dorinda's "JOVANI" outburst at Luann's cabaret show during the "RHONY" finale also came up during the reunion. Dorinda maintained she was not heckling her friend, but Lu felt quite differently.
"She was heckling me," Luann told Andy. "It was terrible. I feel so sad to watch that. I mean, I feel sad that Dorinda doesn't see this and say, 'Oh, my God. I can't believe I behave that way.' I think just her behavior speaks volumes."
Dorinda also said she felt the success of Luann's cabaret show got to her head and may have led to her relapse.
"There were people saying, 'I can't deal with the ego,'" she said on Wednesday's conclusion. "I think she got confused between fame and infamy. My mother always says, 'In the face of devastation, humility should prevail.'"
Luann told Andy, "Yeahhh, I'm not taking advice right now from Dorinda. Thank you for those two cents! I will say my cabaret, to me, is everything. I've found my calling in my life, and if that makes them uncomfortable, that is too bad for them. That's all I got to say."
Andy said he loved hearing Dorinda say she felt there was hope for her friendship with Luann, to which Lu replied, "I think that's very sweet of her, but it's not my vision for the moment."
During the reunion, Ramona Singer told Andy she had told Luann some stuff about her ex-husband, Tom D'Agostino, that made her turn to alcohol.
"Well, I was upset because she told me some things about Tom that I did not know, and so I was upset about that," Lu said, adding that she was "grateful" Ramona told her those things off camera.
One thing she was not grateful for was the story Ramona told about Luann being so wasted at Hotel Beacon that she had to be carried out. Ramona also said Lu was drunk and disorderly at fashion financier Chris Burch's Southampton home -- which several news outlets reported in early July.
"That's a lie. That's a lie," Lu reiterated before turning to the camera and saying, "Ramona, look at me. Ramona, look at me with those eyes. I was never at The Beacon this summer, so that is a total lie. And at Chris Burch's party, I was not kicked out, Ramona. So you gotta stop making stuff up to make yourself look better, Ramona. It's not gonna happen. Nothing can make it look better."
Luann told Andy she felt the ladies "ganged up quite a bit" on Bethenny Frankel during the reunion.
"I feel like there was some plotting and scheming going on beforehand somehow," she said. "I think there was maybe some planning going on, and I really felt like I wish I could have been there to help Bethenny out because I felt like they kind of ganged up on her. They were all in cahoots, you know what I mean? They all kind of agreed with each other. They all kind of had each other's backs. I felt very much that they were in cahoots."
When Andy asked Luann if she had been in touch with Bethenny since the recent and sudden passing of her boyfriend, Dennis Shields, Luann said, "We're in touch with each other. I haven't spoken to her [because] she needs time to heal, and so I've given that to her. We've been texting each other and staying in touch."