Should I just realize it will probably never be?

Ok, so a girl I have a crush on I think has the same crush on me but she has a boyfriend and neither of us are the type to break up a relationship, especially considering I am friends with her boyfriend and have known him longer than I've known her. Not to mention even if they did break up how do I know she's gonna want me and not someone else? This girl could have any guy she wants and there are a ton of guys that want her, so even though I do think she has a crush on me, how do I even know she would wanna be with me and not someone else? I could just be wasting my time here hoping for something that probably will never be. Should I just get over it and if so how? I still wanna remain her friend and possibly keep things open but I wanna tell myself the chances of that happening are probably very slime and I'm better off with a girl that is single.