The ex factor

My boyfriend and I are very happy and deeply in love with real passion and friendship. We just moved in together after 8 months and we both have a child. My daughter is 8 and his son is 3. I’m concerend that it’s too soon after his divorce of which he was only married 3 years and was forced to marry because of his values and there was ababy coming after 3 months of the relationship with her. his ex treated him horrible, she basically put the child before him, she breast fed for 2.5 years and yet he kept hanging on. He loves me very much and is wonderful to me. However, I still have this “anger” of why he help on so long and put up with her. He tells me he’s never loved like this with me and is scared I’m going to leave him because all the drama she creates. The child is very insecure and has no structure at the mothers and we have him 50% of the time. Help