Detachment has nothing to do with ending an R. It is what is required for any really healthy R.
Plenty of people end Rs and NEVER detach. Go look in Surviving for the folks who can't let go of their bitterness and anger years after the fact, who think their ex-spouses are still "doing things" to hurt them years after a D by simply having a decent life with another person.
You cannot extend true compassion, friendship, or support to another person until you quit making anything about them about you as well. That is why detachment is important. You can't take care of you and your own happiness while you keep thinking your every action is about someone else. That is why detachment is important.
I think you may be both so scared that you will not want each other if you detach, that you will find there is nothing there. If so, this is interferring with moving to a place where a healthy R is even possible.
(BTW, in case you or GH missed it, I said that things make a lot more sense given your history, by which I meant my thoughts about the cheating stuff had changed. You weren't in a really long term stable R with unquestioned commitment and monogomy. My thoughts about how much SO has cheated had to do with him not acting like a man who had been in a really long term stable R with unquestioned commitment and monogamy. He seems to at ease in some ways with something different. Serial cheating would explain that. Then again, so does the simple fact of your history.)
With respect to pushing him away when he said he didn't want to go, this is really just a way of "leaving the state" again without having to move. In light of all this history, it is very important that you make it clear to him that there is a way back and what it requires. I'd suggest being very direct about this. I'm not sure if you ever said anything to him or not after your last post about him asking what he should do...
