Move on.
If your crush has a boyfriend then you are not her crush. There is no relationship, you are just a friend.
Don't compare him with your boyfriend, or you will forget how great your relationship is and how much you love your boyfriend.
Nothing. You respect yourself, your relationship, & your boyfriend.
If your friend did that, they're not truly your friend. Of course you can be mad. But keep in mind that your relationship must not have been string enough to break that easily. It's not all your friend's fault, nor your boyfriend's. Maybe you and your boyfriend should have spent more time making your relationship stronger.
This will depend on how you feel. If you want to stay with your boyfriend explain to your friend that you are in a relationship and you are not interested in him more than a friend. If you have feelings for your friend you will have to leave your boyfriend but don't jump into another relationship right away date and see how things go - but remember if you change your mind the odds are your boyfriend will not take you back so make your decision wisely. If you are just undecided and have feelings for both you should not be a relationship at all - you need to be single to take time and sort out your feelings and don't rush into a relationship with anyone.
=I don't know, cheat=
If she is truly your best friend, then you will have to trust her to keep her feelings in check and respect your relationship with YOUR boyfriend. Encourage her to meet other guys and go out.
screw your friend
If you still have feelings for him you can't do much but talk with your best friend. If she is a good friend then she will not began a relationship with him.
That's possible. But there's a chance that he's friend with her boyfriend. If he isn't his friend, there's a possibility that the boyfriend still has feelings for the ex girlfriend and is being nosey about her new relationship
Eat his/her boyfriend/girlfriend and say he got hit by a truck.
Well it depends. Is your boyfriend's best friend recently been dumped? Cause then he could be confused. Or maybe, you make your boyfriend really happy and his best friend wanted to be happy too. You should tell your boyfriend if you really love him.