It sounds as though perhaps your friend has a crush on your crush too...

However! Before making assumptions, I think it would be a good idea to talk to her about this, and ask her how she feels. If she's a true friend I'm sure she will be honest with you, and if you
do both like the same person then you can figure out what to do from there.
But give her a chance to tell her side. There could be another explanation. Some people are just naturally flirty and touchy-feely, and perhaps you are just hyper sensitive when she behaves like that with your crush because you like them, when actually she might be like that with everyone.
Or it could be that she is a little jealous of the attention you are giving to him, and is trying to get some of the focus back on to her because of her own insecurities?
Whatever it is, don't let it come between the two of you. Talk it through and hopefully you can get your friendship back on track.
Always try to remember that guys may come and go, but good friendships are definitely worth holding on to.