Attracted to brother in law :(

I've never been unfaithful at all, but I've been faced with a conflict, I'm attracted to my brother in law. 

I've been around physically attractive men before and they are just another person, but for some reason I feel something for him, that I don't want to feel! Being around them can be awkward because I will try very hard to distant myself and make sure I watch my body language and what I say because the natural reaction to someone you're attracted to is to flirt and it's stressful! I don't want feelings for him!

I hate this feeling and despite my efforts I can't stop it!