What Should I Do ...

Of course I`ve seen this in movies, but I never thought this would happen to me. I`ve been interested in this woman for several years. She`s young, in her early 20s. For years, I didn`t see her often, but whenever I did, there was something between us. I didn`t ask her out becasue she`s always had a boyfriend. I think the same boyfriend. In December, I saw her and found out she was graduating, which meant I wouldn`t see her anymore. So, in early January, I sent an email asking her out for coffee. She was happy to hear from me, but mentioned she`s engaged. Through the course of several emails, it became clear that she has feelings for me, so I told her how I feel. She seems to feel the same way. She said she can`t stop thinking about me. What should I do?