Help me! What should I do about this girl I like? I don't know what to do.?

Dont you think you would regret more of what you didnt say rather than what you did say? If you do tell her then youll never have that 'what if' feeling in the back of your mind. Its clear she likes you so it doesnt seem like a big risk. And if she doesnt give him up for you then she probably didnt mean what she said about wanting to be with you, but it honestly seems like she does