Help please.

nicole
last year my bf cheated on me in November. I had no idea until I found old emails and craigslist ads for hook ups in his email back in April when we moved to Colorado. I took him back and it's effected us real bad. I thought we got over it because things seemed to be better but lately he's been secretive again and weird... I snuck into his email and on oct 19 (the day I left for vacation) he emailed someone close to Denver international for a hook up. there was no replies or anything. I don't know if anything has happened but I don't know what to do. any time I confront him he always starts bawling crying saying how much he loves me and wants to marry me and only me. but hen he gets mad when I talk about or ask about getting engaged or want a baby and getting married. I know we do love rah over but this has been making my anxiety go off the chain. please help :(