People seem to only answer the easy questions on here. Need relationship advice!?

I meet this guy when I was 20 he was 21 he approached me and we dated for about 3 months. I moved across the country for college and have for the past 8 years I have thought about him on and off. I just as of this Jan. got out of a very long and serious relationship and through mutual friend's of a friend he has contacted me. I move back to the state that I have originally moved out of while he was coincidentally moving away from lol...literally the same week I move to back to Cali and he moves to Utah. We have been keeping in touch and just wanted to catch up because it has been over 8 years. He didn't want to tell me that he had a girlfriend at first because honestly it was irrelevant to me and to him because we were JUST CATCHING UP AS PEOPLE nothing more than that. Been talking on the phone for months and now he is back here in Cali for the whole summer visiting. We have hung out and have gotten use to each other again in person. We found ourselves making love and it was the best I have ever had in my life it was so incredibly romantic not to sound cheesy but it really was. He feels bad that he has cheated and I feel bad that I allowed this to happen. I know I am gonna be vilified for this but in all honesty I really didn't see this coming. We never had sex all of those years ago when we 1st met and now we cannot keep our hands off of each other, we also have tons in common and he has gone above and beyond for me and helping me fix my civic. We are at the point where this issue needs to be addressed his girlfriend. I just don't know what to do.People seem to only answer the easy questions on here. Need relationship advice!?
You sound like you have something going and an affair is not the right way to go. This is complicated I can tell you that... I would try a long distance relationship if he can't move back to California (and don't expect him to). He should probably break up with his girlfriend seeing as he has cheated on her and that is rather unfortunate but, at this point you really can't spare their relationship. If you have true feelings for him I would go for it and if you are unsure I wouldn't.People seem to only answer the easy questions on here. Need relationship advice!?
well its enitrly up to you what you do you can either ask him to leave his girlfriend for you or you can just think it was fun whilst it lasted. however bare in mind if he cheated on his girlfriend think about when he goes back home if someone else comes along better than you then he might cheat on you if you got together. so its up to you if you want to take the gamble.