Cheating

I've been with my boyfriend for over a year now.. being a sports player he goes here and there to play. last season of the game he had a few drinks ended up sleeping with he's ex girlfriend 🤦🏻‍♀️ he never said anything until the biatch called telling me he slept with her i might be pregnant with he's baby..
He apologize he's sorry he said .. i get so mad ...everything he says to me i just don't trust him and i always disrespected him after wat he did
i know he's sorry he quits drinking but i cant move on its like so hard it's always in my head😭😭😭
should i leave him i'm confused...
how does someone move on with this things