Why do they think you want to be friends?

I wrote about an exboyfriend in one of my domestic violence posts. He was the guy that my exhusband had threaten to kill when he broke through the screen at my house.

He had broke up with me the day after, but he said it wasn't because of the incident...which I know part of it had to be.  He was a great guy, and the only guy in my life who after he broke up with me, I didn't have mean feelings toward.  I still get butterflies and miss him terribly.  Why is it that it still hurts?  I mean it has been 6 years since we dated, and to see him or hear from him still hurts.

He has become friends with a family member of mine.  She let me know over the summer that he got married. I was heartbroken, but why? My god it has been 6 years!

He found me on facebook and sent me an email.  I have been teetering back and forth on whether to respond. After he sent me the email, and I never responded he sent me a "poke".  Now I sit here debating on whether I should answer.  I don't want to, but I feel I should.

For several years after he broke up with me, he would on occassion message me. Which was hard, but he made especially harder by telling me how awesome of a person I was and that some guy will be happy with me, and that he can't believe I'm still single.  Conversation usually ended up by telling me that he was sorry he hurt me, that it was all him, and blah blah blah.  This would make me cry every time.  After not hearing from him for so long, I finally was able to go on...or so I thought. Until my family member told me about his marriage.  Then that led to several days of morning that relationship. Now for the record...I wasnt devestated about it...I just wished I was the one he was married to.

So tell me...have you ever been unable to let go of feelings you once had for someone for 6 years or more?  And also, would you email him back?  I'm in need of opinions.  Please help!