Annoying

When I first met my boyfriend I hung out with a boy and he said I cheated for doing that I haven't hung out with no boys since and we been together going on 3 years we are expecting our first baby together in October idk how I'm gonna be able to raise this baby with him if all he does is accuse me of cheating and everytime I tell him we should break up he says it's because I have a side man idk what to do anymore