How do I move on and forget?

Me and my best friend have been friends for over 5 years now, and have always had a romantic interest in each other. When we first met, she was much younger than me, and what I really mean by that is she was 14, and I was almost 18. We met in a computer cl in high school. fast forward a few years, when out friendship strengthens, we become closer, and still have a strong interest in each other, at this time she was around 17, and I'm 20. We've always been in that situation where either I was seeing and she was single, or she was seeing someone and I was single. Now that she's 19 and in college, and I'm 22 with a 14 month old daughter. Her parents are much more open to the idea of us dating. There's just one issue. I'm single and she's seeing someone. He a great guy. really "nice"... Never gets angry, or impatient, rarely if ever displays any negative emotion, or actions towards others, I'm not like that. I'm more expressive, and tend to speak more of whats on my mind good and bad. We discuss all of the time a future together (between me and her), talking about plans on raising kids, designing, a house, where to live, and get married. wedding plans. all of that crap. while maintaining enough space to keep her from cheating on him. I love her more than anyone else could ever imagine. She has no idea how I feel, or how much she is actually on my mind. We've both agreed that, we know each other well enough that if we were to ever have to the opportunity to be together that we would have nothing to worry about as far as hurting the other. and we are mature enough and smart enough to know how to handle a break up with minimal effect to our friendship, and know to expect some effect on our friendship. but temporarily. My point is is that I'm madly in love with her and they are much more perfect for each other. I'm not the type to do anything to ruin what they have, so I've accepted the fact that I just have to be patient and wait for what "may" or "may not" happen. My feelings for her have inhibited my dating of other girls, because I don't think it would be fair to them. How do I move on and just let her be happy, and be legitimately happy for her? and find a way to make myself happy without her?