Should i fight for our relationship or let go if it kills me?

Clearly you are both extremely immature. You are into the drama of the whole thing and not trying to fix the ridiculous pattern this relationship has of becoming constantly unhinged. Men look at other women. If you think you are going to prevent that, you are a fool. If he does not look at other women there is something wrong with him. I am sorry you were cheated on, but that happens to most people. Fix what it is within yourself that is causing you to take your issues out on him. As for him, he is BOUND to get sick of the fighting and drama. If he DIDN'T consider whether this relationship was wrong for him he would have to be stupid. Nobody can carry on in a toxic relationship forever and stay in it despite constant arguments and breakups. It seems to me you are looking for a guy that will only ever look at you and never, ever leave you no matter how miserable you make his life. THAT IS NOT REALITY. If you both want to be in a grown up relationship, it is time to start independently taking care of your own issues and then acting like adults in your partnership.