She knows what to do but doesn't want to do it. How do I convince her?

One of my close friends just told me a weird but interesting story. She found out that her new man cheated on her with his ex and got her pregnant, anyhow she forgave him and married to him. Now that they're married she doesn't want him to have anything to do with the baby, he can't buy anything for the baby. So I asked her "what did the baby do to you? " She said she's justified now because she's his wife and because of the "baby" they're having problems because she doesn't want him to buy anything for her(the baby). I didn't want to be harsh with her but I told her that she knew all that about him and stayed and got married to him, I had to ask her if she wants for him to choose her over the baby and she said yes because she's his wife. I'm her friend and yes he's a pig for cheating on her but as I said the baby did nothing to her. I honestly don't know what to tell her anymore because she isn't listening.