Abortion

My mum is 41 and she's pregnant. She's told my little sister that she's going to have a baby and that she can tell the class when she goes back to school but she wants an ABORTION. My dad wanted another baby but here she is saying that she's going to get rid of the baby and now he's leaving her. I've tried to tell her that it's wrong and you shouldn't take an innocent life and she doesn't even have a proper reason for one. Please help me because I'm honestly at the point where I want to leave and if she does all this then I will NEVER forgive her. And another thing is that she was discussing baby names and everything and all of this was getting my 7 year old sister all happy about being a big sister and now she just wants to take that away. I don't care if it's her choice because there are so many people who want a child but can't have one and here she is taking it all for granted. She said that no one will help her but I would happily take some time of school to help but she doesn't see that. All she cares about is her own welfare and not her baby's.