trust issues

me and my bf have been together since we were 16 he’s 19 I’m now 18 we have a baby on the way I’m 15 weeks. Well a bit ago he was messaging this girl it was him basically entertaining her. And then has like several of his exs posts and many other half naked girls. Well now I just have trust issues I feel he’s always texting girls or hiding them. We have been together for this long and I don’t even know his password he has never posted me or even announcing the baby or anything. I post him all the time. And when he uses the bathroom he will go in and forget abt his phone and come back out and get it. I feel I’m only staying for the kid but I’m not sure I don’t work and he supports us.