Bf asked ex to move in before I moved in?

Simply stated. Current bf and i were separated for a year and a half and in that time he and the mother of his child slept together and spent a lot of time(but never technically got back together). One day out of the blue, he tells me to leave my bf at the time, and to move in with him, that he needed me back. I left my bf and moved straight in. I missed him so. Well baby mama didnt like that too much. She went crazy. Started texting me..stalking my social media. I blocked her. I have been living with him for 2 years now and I just unblocked her messages to see what screenshots she sent. It was him.. Begging her to move in 2 weeks before I moved in. i am crushed. What would you do? Its been 2 yrs and we have been so happy.