I was in a similar position as you when my ex suddenly bounced back about 6 months after the D was final. He was/is most likely a sex addict who was involved with a trashy OW also addicted to drugs. She got busted stealing oxycontin from her job (she was a nurse!), got her license revoked, and had 4 felonies and probably did jail time at some point. He bounced back at me during that crisis.
I gave him 24 hours and a couch, he stayed 2 weeks. What did I do? I made SURE he got kicked out. We had the umpteenth argument over his negligence and laziness, he was drinking, so I called the cops. Told him either leave or have the cops escort him.
You have to take a hard line with your ex. I had 2 minors at home at the same time (one was 15, the other 17). I didn't focus on anything about this with them. I kept them out of it as much as possible. Your ex has to fix/heal/cure herself.
Petition the courts for custody of your daughter if you have to, and go after this woman for child support.
I know this sounds harsh, but putting a steel rod in your back will make you feel much better and much more empowered. You are putting yourself out as prey for your ex. Don't do it. All the "explaining" and "conversations" you have with her are falling on deaf ears. She has to decide what's right and wrong for her, not you. If you have to, get someone there with you (your brother?) to help you get her out of there and get custody of your D. I would think it is a no-brainer to any judge to award you custody if your ex is a bartender, not making much money, no home/place to live. It doesn't matter to you where she goes or what she does about it. Get her out and tell her your D will live with you and don't make it a decision for her, just do it.
