How can I get my friend to stop hating my boyfriend.

My ex and I broke up a few months ago and now we are back together. Now she's telling me to keep him away from her cuz she hates him. She never really liked him because she felt he took time away from our friendship. On another note, when she has a boyfriend, I never see her. Is she always going to hate him? Shouldn't she support me no matter what my decision was?