What would you do in my situation?

I have had a trust issues with my boyfriend for the past year. I found out some "things". I started to have that gut feeling again that he might be messing around on me. I hacked into his e-mail acct. I couldn't believe my eyes! I was 100% correct. It was more then what I thought. It looks as if he was on craigslist looking for with other couples & even talked about being BI. I have lived w/him over 3 years OMG! Should I believe the emails? He is blaming our ex-roomie of hi-jacking the acct. & sending the messages. I can't see that happening tho????