They are probably not a very good friend and you should seek friendship elsewhere.
Get the friend to talk to him and if the friend won't slap the friend in the face
Slap him
If your boyfriend wants to leave your best friend to be with you again and this hurts your best friend, then hurting her is unavoidable. That is assuming you really want this person back. Without knowing the circumstances of why an exboyfriend would now be with your current best friend and without knowing why the two of you broke up to begin with then all that can be offered is support to you and assuring you that getting an exboyfriend back isn't all that you are. Be all that you are and whether it is getting back with your ex boyfriend or finding someone new, you will be happier either way. Your happiness is not contigent upon which boyfriend you have nor even having one at all. If you are unhappy, you will continue to have problems in all relationships. Be happy.
i think that you should tell your best friend that if she goes out with him that you will not be her friend
well, if she broke, show sympathy. then become her friend. slowly but surely, you'll get there.
try to steal his best friend and smooch in his face
Since you broke up with your boyfriend it is highly likely that now that he is dating your best friend you are either jealous and it probably isn't love at all, but you just don't like to see him date your friend.
He probably broke up with you because he was cheating on you with your friend. Then he showed up with your friend.
No. She broke up with her boyfriend, Hayden, about 1½ months ago.
Unless they broke ToS, no, but if they did, you report them.
I don't think it's a bad thing, because of the fact the he broke up with you.
I think she wanted to break up with him anyway.