First time mom & terrified😔

Arielle • FTM expecting a baby girl May 28th💕👶🏽
I have been trying to talk to my child's father and he has decided that he doesn't want to be involved. He refuses to tell his mom, sister, or any family that he has another child on the way. He wants to keep her a secret. My child should not be treated that way being as though it's not her fault and he already has one child. Needless to say we broke up because he lied and cheated and decided he wanted to be with someone else. But now im pregnant with his child and I'm due May 28. First time mom & terrified. He has said he can't/won't help because he doesn't want to (he's a 35 year old grown man😒). I asked him to at least b there when she's born and for support and he said he will see what he can do. I haven't even had a baby shower yet(if I even have one) because I don't want everyone asking where he is, idk if I can handle the embarrassment. I thought he was the one and we had a great relationship, I bragged about him to all of my family and now this!!!! I want to message his sister & let her know what's going on in hopes that maybe she can talk to him or at least be of some support but idk if I should or not.  Should I reach out to his sister ??? Help ???