I don't know if I can go on

I've posted a few times, but I just wanted to share where I'm at in my journey. I started therapy a little over a month ago. During my sessions I explained that I had RJ, but to my surprise, my therapist seems to think I don't have RJ. He actually thinks my concerns are valid and quite normal. Basically, I can't get over the fact that my gf used to have sex with a new guy weekly before we met, meeting guys on dating apps and clubs exclusively for sex. My mind always turns to disgust, because for the longest time, I always told myself I wouldn't date someone who does that. I have a hard time wrapping my mind around it, because I myself, only had a handful of one night stands in my early college days. The truth is, if I had known this about her before I fell in love with her, I wouldn't have pursued a relationship with her, but over the months, she has over shared details about her sexual past that occupy my mind way more than I'd like. She's had past relationships and none of that bothers me. I guess what I'm trying to figure out is if I even have RJ. I just don't know if it's just deeply engrained personal values or societal pressure. The other day, we had a party and this guy initiated a game of never have I ever. My gf was the only girl that basically drank to every sexual question, as in she had done them. Then he kinda started to cause tension between us on purpose and we had an argument later that night. She then proceeded to tell me how she slept with his friend at one of his parties and wanted to tell me because she didn't want me to find out from someone else. This has just triggered my anxiety more and she told me based on the off chance that I hear from someone else. She knows about my RJ and we've spoken about it a few times now. I guess I'm just at an impass now, because I just keep thinking about whether or not I would be happier if I left the relationship, because everything about it is great except for these thoughts that eat at me constantly. In fact, our relationship is better than any realtionship I've had before this, so it feels impossible to let go of something that feels so good. I'd like to keep trying, but it's been nearly 5 months of dealing with this. It has improved, but it's still there. I want to not care, but like most people here probably know, it's easier said than done. Some days I feel great and like she's the most wonderful person ever and other days, I feel like I'm better off alone for now and she's better off with someone who accepts her for her past. We are temporarily living together at the moment so ending it now isn't even an option, but we'll be moving into our own apartments at the end of the year. I just need advice and maybe support for getting through this. Thank you for listening.