I have fallen for this girl who has a boyfriend and she is absolutely everything I want. What do I do?

I met her at work. I don't go for every girl I see. I actually go for girls based on a certain feeling and it has only happened one other time in my life, but that girl didn't give me the chance. Well, anyways, I like this girl and everything about her, she is definitely what I have been waiting for. She has a boyfriend and they have been together for 5 months. Thing is lately, they have been going through a lot of problems because the guy is being a complete douche to her. I know there is an attraction between her and I, and she knows it as well. Thing is she isn't sure or ready to break things with her boyfriend just yet, it may be that she is still unsure of her feelings for me. What should I do? Should I win her heart over like I think I may be able to, or should I wait a little longer so that her boyfriend can continue to be his douche bag self and lose her like he is starting to do? There is no question that she is my hearts sole proprietor.