Fell for the wrong person and missed the boat

I am going to do my best to keep this short.

I met this stunning beauty when my wife and I moved into our apartment. I recognized my affectionate adoration immediately and understandably squashed it as I was married (not only that, she was engaged). I didnt obsess over her or anything, I just knew her as the pretty and sweet girl downstairs. It was never a problem for me and life went on (no flirting, no nothing). I didnt spend a single extra moment thinking about her. As time passed, my wife and I became friends with the girl and her fiance and routinely spent time with them. The four of us had some good times together.

As my wife and I lived on, our marriage (which was already on shaky ground) began to deteriorate. She called for a separation. We had grown apart and had essentially become roommates. I fought long and hard to try to keep her....but it was wasted energy. I discovered that she had been sleeping with someone and I called for a divorce. It was easily the worst time of my life.

Fast forward a few months. I began to hang out with the couple again. They had moved out of the apt to a neighboring town before my separation. I really did enjoy their company and they did what they could to make me happy. However, I felt that the girl was being a bit flirty with me, but I assumed it was b/c she was tipsy and I didnt think much of it. However, the look in her eye continued the next day and again when I saw her a few days later.

I went away for a month and we communicated via email every so often. It wasnt over the top by any means, but simple friendly conversation. However, I slowly began to have feelings for her which took on a life of their own.

Shortly before I returned home, she had called off her engagement for her own reasons that had nothing to do with me. I saw this as an opportunity to explore or share my feelings, but I didnt b/c I was also friends with her fiance. I did what I could to remain friends to both. I spent time with them separately talking and trying to keep things happy. However, I could not keep my feelings for her from growing and taking over. I began to feel that I was boxed in and I had to act. I had to tell her how I felt even if it meant that I was a bad friend .

Valentines day was nearing and I used it as an excuse to speak my heart. I sent her meaningful flowers along with a note expressing my affection for her-but I remained anonymous. It was a stupid decision, but later that night I told her it was me as I had just discovered that she had begun dating another man. I didnt see the use in keeping quiet any longer.

True to form, she was nothing less than touched and grateful. She did say that the thought had crossed her mind but that she never entertained the idea for obvious reasons. She went on to say that she could not return the feelings even if she were not dating someone. I expressed my appreciation for her honesty and wished her well as I was going to have to distance myself from her to put my feelings away in hibernation.

I have been moderately successful in getting my feelings under control as I have not spoken to or seen her in about a month. Ive since learned that I will have to move 3 hours away for work and I cant help but to want to see her once more as I will likely never see her again. She has a special occasion coming up and I am tempted to give her a call to congratulate her and maybe chat for a bit. This may make me a bad person as I know that her former fiance's heart (someone I do see as a friend) is torn to shreds over her and she is presumedly happily dating someone else. I dont know what to do.... Ive never acted on feelings like this like I am now. I just cant believe that this is the end...Please someone advise me. Tell me something hopeful or tell me something harsh. I just need to hear something.

I should also say that she was quite understanding when I told her that I was going to have to slip into the shadows for a bit. She went on to say that if I ever feel comfortable contacting her to do so.