Make him file the papers and end things if its' gonna happen. Act like you don't give a damn.
When he DOES come back since YOU've been showing him indifference he's going to realize he has some work to do.. if you act like you want him back and show desperation tehn he's giong to be a lot more pompuos and full of ego when he comes back... you want the FORMER situation, not the LATTER.
So why is it they get interested again when you show no interest?
When we were dating, are mutual attraction is what made the relationship progress. Now that we're estranged, why do the rules change? Is it because we always want what we can't have?