This is going to differ a little bit from what the others have said but here goes anyway
X has made a move, this is good but you might want to remember that X is probably scared as hell right now. He isn't POSITIVE he hasn't burnt all of his bridges with you...this is more like a "sticking the toe int the water to see if it's cold" thing at this point if you ask me.
He has ventured to you that he would like to get back together, that is a HUGE step BUT if you start making all kinds of demands right off the bat then the chance is good he just might bolt again. If in your heart you would like to give him a chance again then I would recommend starting over from the beginning...start with a beginners mind. Treat him like you would a new man in your life (hopefully that is what he will be ) using the DB principles to build a new R with this man. Set boundaries yes but not demands or ultimatums...is this something you would have done a year ago if he had come back to the M instead of going with the D??
Zoo
"If patience is worth anything, it must endure to the end of time. And a living faith will last in the midst of the blackest storm."
- Mahatma Gandhi