Struggling with trust

Hello I rlly need opinions right now. I'll try to make it short. I'm in a 2 month relationship and everything is more than great. She said it feels so real and she never felt like this and it's the same for me. We once talked about our exes because they both weren't great ppl. So her ex wasn't good. He ghosted her and cheated on her and stuff. And yesterday she told me that close of the end in the relationship where she was ghosted and ignored she downloaded a character ai bf app and received attention from another place which means it was cheating. And she said it's reallyyyy cringe to her now and she's ashamed of that and 1000000% against that stuff now. ( I asked her why she didn't just break up and she said that she tried multiple times but her ex always insisted in taking breaks). But there's that sentence ppl say it's " once a cheater always a cheater ". So I got concerned and confused. I'm not sure if a character ai robot bf counts.... i talked to her and she said she promise me she wouldn't do that to me because it's a selfish thing to do and if there's a problem and she doesn't feel loved she would tell me and if it's not better then break up. She also alwayssss talks bad about cheating ppl. That she doesn't understand them and stuff. She always seemed pretty loyal to me it was always easy to trust her. But now that happend and Im concerned. I don't know what to do or what to think thats why I'd appreciate some opinions on that and help reallyyy much. Thank you.