Well where to begin??? Lets start here>>> my ex husband and i recently divorced a year ago we seperated 3 1/2 years ago. Needless to say I was the one who walked out I was 17 when I met him and 24 when I left him he was 27 and 37 ..When I walked out I had a 2 mnth old 4yr old and 9. We were suppose to seperate I needed time to figure out my feelings we never went to consueling instead ran in the wrong directions he moved on a month after as did I a few months later. But we've always maintained a close relationship always talkin about what if.... well a couple months ago our conversations stopped ive come to find out hes asked his new gf to marry him. Now i find myself so confused. shes put all these walls up between us hes not allowed to talk to me or see me at all. This summer he took our kids and didnt return them wouldnt let me speak to them or see them at all. Shes always had a problem with him givin me cs so hes always had to sneak around to do it. So ive had to hire an attourney to get all that straighted out. My kiddos seam so lost and confused they love mommy and daddy both and i know that ive always kept our relationship open letting him have accsess to our kids whenever hes wanted. and for a long time all he wanted was his family back even though he was with her but never left her hes always said he didnt want to be alone that hed leave her if i took him back. but i just didnt know if thats what i wanted and i guess it never bothered me since we still spoke everyday. now things are strange my babys miss there daddy and i hate the thoght of our next 15 yrs being this way. I know alot of this is my fault I just dont know how to fix it....

I know that its not all cut and dried is it. We cant turn our feelings off no matter how they drive us nuts. Maybe you miss the security of knowing that he is 'there' for you? Clearly his gf doesnt want you in the background should you ever change your mind and say lets give it another go.
You seem to have been seperated a long while but have remained friends. Could it be the friendship that you miss? I think sometimes while we have an element of uncertainty we kind of get stuck because we are fearful of both moving forward or going back. Maybe its a normal reaction to the possible loss of something even if it is more the friendship than the chance of what could have been. Id be pretty devestated if I had to lose one of my friends. It would still hurt.
Maybe you could find a way to have one final talk with him just to clarify things between you?
Good luck.