I'm quite attracted to my best friend's wife and we have decided that we won't act on our feelings. What we feel is real and we feel guilty.
How you told your friend about these feelings?
I don't know how to face her.
Feelings can't be helped but you shouldn't act on them. Not only would you hurt their marriage you would also hurt your friendship with your friend if you interefere in their relationship.
I'm madly in love with her and I can't help it.
It's not good to be attracted to your friend's partner and while you're feelings are real, you need to make an effort to move on and get over the attraction. If you act on these you will permanently damage your friendship, probably to the point of disrepair.