21st birthday

Ive been with my boyfriend for 5 years, today is his 21st birthday. We have a 6 month old and we recently almost ended things because I saw a message to another girl. He was telling her how gorgeous she was and it hurt. Anyways since that we've been trying to work on things this barely happened 2 weeks ago. I can't say I trust him 100% but I agreed to work on things so I'm trying. Its not just that , it's other women I don't really trust. I won't be able to see what he's doing or who he's with. The messages are still fresh in my mind so I feel a little bad about him going out tonight. I'm not gonna make him stay home on his 21st birthday I'm just feeling a little weird about it and I don't have anyone to talk to.