“In my life whenever I get close to someone I lose interest and want to run away and always do. But he was different”

No. He wasn’t.  You did the exact same thing to him. Also, from all your write ups, it’s clear you never really loved him and probably never will if you get back with him. You’ll only ruin the good thing he has going on now with someone who values him.

“I miss him so much but I do not know if it is because he is with another woman now. She could be the “one” for him. He appears happy. It is killing me, my heart is aching”

Again, you never really loved him. His happiness is killing you and aching your heart. You’d feel better if he was emotionally in pain and suffering after you left him.

“It was a very intense, obsessive relationship. I felt as though I was being smothered at Times. Our sex life suffered as a result. He was a passive person which irritated me sometimes. He would agree with whatever I said if I pushed it enough. However I loved him as a person. He loved me, we had good communication, we talked all the time, we were true partners”

This appears contradictory.  A relationship with good communication as you claimed above isn’t one that is intense, obsessive or lacking in sex life I believe. It’s really hard to tell which is which as we can’t hear his own side of the story.

You also mentioned your friends didn’t support your relationship with him even though you claimed you were happy and loved him. You need to ask yourself what kinda friends you really have.

You don’t love him, you ended the relationship, he’s moved on and you should as well. Now you’re free to try out other experiences with guys, be individual and single like your friends so, it’s actually a win for you. However, what’s behind door number 2, 3, ….n might not be what you expect in a relationship.

Try seeking therapy as the issue might be deeper than we think. But most importantly,  be honest with yourself.  Don’t play with the lives and emotions of others. What goes around,  comes around. Move on. Go out on dates, meet new people and you’ll see, once you find someone else you think is mr right, again,  you’ll no longer be bothered about you ex.