I feel hate towards by best friend?

I've had feelings for my long time best friend in the past and he knew it the feelings weren't mutual. Lately he started saying how much he likes my sister and wants to go out with her. He knows how much I disagree and that it bothers me. I've been very distant from him lately and accuses me that I'm a "bad friend" because I'm not happy for him. He hasn't yet told my sister than he likes her but plans on doing it. I know my sister wouldn't go out with him. In fact, people in my entourage were hoping him and me were dating. I feel a lot of disappointment and a lot of anger. What should I even do? Thanks