Stuck in a bad situation? Don't read if you don't like reading long things. Thanks.?

My fiance and i have been together for a year and a few months. Im starting college in the fall and we plan in getting married in August. Thing is... When we first started dating after a few months he got drunk with his buddies and called me when he was drunk at 2am after he told me hed call at 10pm. He tried saying he wasn't drunk but i knew he was lying. Then the Next day he told me he thought someone probably drugged his drink. Which is the STUPIDEST lie ive ever heard then finally a month after that he told me he did get drunk and he was sorry for lying but he was afraid id leave him if i knew he got drunk. But he knows i wouldn't have dumped him being since the beginning i told him honesty is most important to me and i forgive easily if he makes mistakes but i wont if he lies and i find out the truth. So ever since then i have a hard time believing what he says. I know he didn't cheat on me cause his buddies and his aunt that was there said he didn't. But the lie still eats at me. I don't take lying lightly at all. And we live 4 hours away from each other because he works out of state and i am staying here for college and i have 2 years of college so it makes it even harder to trust him because with his job he had to stay in the state his job is at for 7 days and then he gets 7 days off to come here with me so for those seven days i worry about him lying about what hes doing and plus the whole 7 days he is gone is really hard on me because i miss him so much and love him and hate being away from each other for that long. Any Advice? Thanks.