Boyfriend problems

back story: I'm 16, 31 weeks pregnant with a little boy. my boyfriend (17) is continuously snapchstting girls, inviting them to parties, ect. He knows I know about them bc I confront him about it. and still continues to do it, today I was talking to this girl and she told me that he asked her to hangout on NYE and she said "no you have a gf and a baby on the way" and he said "it doesn't matter,she won't find out."