Daughters father still trying after 3 years

My daughter's father and I have been broken up for three years now. He left me when I was 3 months pregnant for our daughter and started dating another woman who he now has a child with. He is still with her but he continues to try to sleep with me and flirt with me. I have been with my boyfriend for a little over a year and have told him all about this. We even tried to tell my daughter's fathers girlfriend. She believes I'm the one whose doing it and he's done nothing wrong. She now hates me and has an issue with him even calling to talk to our daughter. I've tried everything and don't know what to do anymore. Any ideas on how to handle this?