You wondered if a relationship is worth it...well, the risks are really not that great. If he is your friend and you are really fond of her--then of course it is worth it. I'll give you some insight to me.
My ex cheated on me when I was in Afghanistan. The guy she cheated on was my best friend. When we split and divorced, I supported her and hoped for the best for both of them. In time, she found out he cheated on her and they split. Now, she has someone new.
I really like this guy. My daughter (which I share with her) likes him as well. I care about my ex and want her to succeed in life and romance. Because I care for her and like this guy, I do everything in my power to support their new found romance. I have bought him shrimp to grill when I found out he likes shrimp. I offer to sit my daughter and her other kids if they want to go out. They are going to a Titans game this Saturday and I offered to watch all four kids that night so they can go enjoy the game.
My point is that if your friend cares about you and her--he will support the two of you. The slang term of "bro's before hoe's" really only applies if he is your true friend. You are not 'dissing' him if you like or love her. It is what you feel and if he does not support that--then maybe he is not as good of a friend as you thought.
A true friend would want to see the two of you happy. Life is pretty short. There are no guarantees in life. If she makes you happy and you make her happy-give it a shot.
Sit down with your buddy and tell him your feelings and see what he says--he may surprise you in the end.
Good luck and keep us posted.