My bf makes me uncomfortable

I’ve been with my big for a year and like 3 months. At the beginning I had caught him messaging other people. I decided to stay with him and it’s just been one thing after another after I caught him multiple times. So I don’t exactly trust him but we’re working on it. Today he said his buddy invited him to a get together because his gf is gonna give birth tomorrow...(like a tf that’s stupid reason and bad timing but ok..) and he said we’re going..I don’t wanna go because there’s gonna be other girls there and I’m not gonna be looking dumb if one or a couple of them are the girls he was talking to behind my back. I told him I feel really uncomfortable and I told him why and he said that either he’s going alone or I go. Even after I said how uncomfortable i was. What do I do. I don’t want him to go I don’t want to go.