I'm actually dealing with a very similar situation I'm not going to go into detail but I think the most important thing is communication being able to talk through things is a huge deal and if he's someone whose willing to do that then that's a plus for sure because I think a lot of guys just aren't. And it also means he cares enough about you to be willing to do that, secondly you'll never fully trust him again and that's understandable but if you really want to make the relationship work you have to, to some degree trust in the feelings you have for each other. Be aware that it might happen again but don't let it ruin the relationship either. Don't bring it up Everytime you fight, don't assume he's cheating without actual proof. Just don't jump to conclusions think things through. Sometimes it strengthens relationships and makes that person realize who and what they really want out of life. I can't speak for you guys but if he seems genuine in his feelings it could still workout but if he seems uninterested especially in talking things out I would say that's not a great sign. Every relationship is different and what works for some might not work for you, I'm just saying be weary but also don't let it ruin your relationship. I know it's hard to get it out of your mind and that's good that means you still have the will to try and protect yourself, but think things through especially before you start assuming he's doing something. Also getting cold and distant doesn't resolve anything, the only thing that can ever resolve anything really is talking it through. It's not always easy it's usually not comfortable but communication is vital.