BD has a gf.. &she doesn’t know I’m pregnant

My ex recently got with a girl and moved in with her. Well he told me he had no where to go and already paid his half for the month and was sleeping on the couch until he found somewhere to go. Manipulated me so bad to the point I believed him. Well we were having sex in June. Did 4 times. And I turned out pregnant. Well he disappears and I find out 2 weeks later I’m pregnant. I know for a fact it’s his baby. I have not slept with anyone else and he came and talked to me saying he wants to do this with me and would see me the following day. He never came back and it’s been 5 weeks almost. Well he’s still dating the girl she has no idea I’m pregnant with his baby and he’s getting to live this good life and no worry. Should I text the girlfriend and be super friendly and apologize but just tell her I’m pregnant or should I leave it be and take him to court when I have my baby and get child support? Thank you😭