Struggling to get over my boyfriends past

I (26F) have been with my boyfriend (34M) for 1.5 years now. He’s the first man that I have been in a serious long-term relationship with, and i’ve only had 5 sexual partners before. So he is pretty much my “first” for quite a bit of things, especially relationship wise. Him on the other hand, has had 2 long term relationships. He has 2 kids with both of his exes, and used to live with them as well when they were together.
So he has pretty much experienced everything with a woman and it honestly kills me some days to think about it, to the point where it’s effecting my mental health so bad. He used to provide financially for both of these exes, gone on trips with them, and living like they were ‘married’ essentially.

I can’t get over the fact that he has done already the most intimate of things a person could do with their partner, and the fact he has done it with 2 different women just eats away at my brain. Even him having 2 BM’s is too much for me to handle (one of them isn’t involved in the kids’ life).

I absolutely hate the fact that he is in constant communication with one of the exes. She is an absolute nut-case and is constantly asking him for money (unrelated to the kid), asking him for help for personal problems, and still texting him and occasionally asking to hook-up, or her still saying “i love you” to him. He doesn’t respond to almost 80% of the things she messages though, unless it’s about their kid. But it’s the fact that she is still messaging him nearly every single day, asking for whatever she needs or just trauma-dumping on him.
I have caught him in the past (when we started dating) send money for nonsense essentially.

It bothers me sooo much that his “past” is still present with him to this day, and unfortunately always will be. I have been very honest to him that I don’t ever want to meet his kids at any point and basically want nothing to do with them at all.

I don’t even see myself moving in with him at all since all I can think about is “he’s already done this with multiple women” it’s not a new experience for him, it is for me though. I can’t stop thinking about him being with these women and still having to talk to ex probably for the rest of his life. Me thinking about his past is slowly killing our relationship and I do try to not think about it but it is insanely hard. My mental health has been slowly deteriorating thinking about it and making myself miserable to the point where I don’t feel happy anymore.

Is there any way that this negative thinking passes? Or should i just call it quits with him if it’s making my mental health this bad?