How to move on from your partner's past?

I'm 24 M Indian. I just got into a relationship with 21 F Indian and I knew that my partner had multiple body counts(single digit). She told me what things she did in the past and I was kinda okay with everything until I got to know about this --> She told me there were some boundaries of her and she still isn't telling me somethings that happened in past and I'm a person who wants to know everything. But still I was okay with it(She said she will tell me later when she feels like telling me.) So while talking she mentioned something and I started overthinking about it which lead me to thinking something. So I just said that you don't have to tell me exactly what happened but just say Yes or No because I'm overthinking a lot and it's fucking my mind. She agreed to it and I started asking my questions. And guess what!!? I was right. So apparently for experience she hookedup with a black dude(yes BBC). At first it didn't hit me that much. But now it's fucking my mind. There's a term called Retroactive Jealousy that's what I'm going through.
All I'm thinking now is how can I be with someone who fked a man with bigger D than me. Will i ever be enough? Also the thoughts of a black dude fuking her so much that it's making me nauseous and what not. She knows it's hard for me to swallow all this and we haven't talked about sex after that because it feels awkward now.

As a Indian I just wanna know if anyone have been through this, or How can you accept this. Ik I'm wrong here, I have accepted past doesn't matter. I watched some videos on YouTube that really helped me with the thinking process but it lasted for 3-4 days, after that all those thoughts started coming back.