Abused women

Why do abused women keep going back to their abusers?

My sister has been in an abusive relationship for right at a year. Her and the baby left. She went back for some clothes (and she was thinking about giving him another chance) and he choked her , pulled a knife on her and made strip naked and lay on the bed. She got away and called the cops. She took out papers and a restraining order. She even went and got temporary custody of her baby so the dad has no rights for the next 6 months.

This isn’t the first time she’s took papers out on him. Last time she stayed in contact while he was in jail and dropped the charges. I thought this time was different because she moved back in with my mom. She seemed different, she was seeming happier. But on Mother’s Day I saw that she was still texting this guy. We think she’s going to see him but at least she doesn’t take the baby with her , actually she doesn’t do anything with her son.

I’m so confused. Why would you choose a deadbeat over your child? Why would she go back to someone like that? He told her he was going to kill her and then kill himself.

I don’t want her to end up dead.