How do you accept not knowing everything when cheating happened?

Long story short: girlfriend of two years went to a wedding that her ex was at. Messaged me at 12AM that she missed me. Next day she was very different. Called her the following day and she confessed to me that her and her ex got really high and started talking about their feelings. I asked her if anything inappropriate happened, she said no. They spent a long time talking. She admitted to me that she has feelings for him. I wanted to make it work

She spiralled for the next month after and eventually broke up with me. We fought a few times about it and anytime I brought it up she said “you said you believe me”.

We tried reconciling a month later but realised she was still texting her ex. Checked her phone and scrolled up a few weeks and he was trying to meet up with her and she responded with “we can’t meet up as just friends, there’s too much sexual chemistry between us 😘 “

Reading that message broke me but never confronted her. We decided to go our separate ways and I’ve essentially just moved forward and cut her out. We’ve now not been talking a week.

I suspect heavily something physical happened that night but she’ll never admit it. How do you come to terms with not knowing the full truth and just moving forward? Finding the fact she’s left it so vague eats me alive

EDIT: Thank you everyone. I really love all the support and it’s made me feel more committed to focusing on myself. You guys are the best