Bad choices

I really, really, really miss my ex. We are too much alike and it causes some friction. But we are so on the same wavelength it's unbelievable. The chemistry is outstanding. We both want each other back but it's too late - he's married with a child now and I told him I respect that, though he tries to make me his woman on the side. At first I got excited and started to go along with the idea but I have since pumped the brakes before we got together (I sadly must admit to virtual activity however, which I deeply regret. I know this was wrong and hate that I engaged with it). Still, no matter what our chemistry, this isn't possible, at least, not if we want to be decent people. He still wants to move forward and I don't, which he has finally accepted after pushing me a lot on the issue. Which just made a small rift and also makes me disappointed that we made something that could have been great (friendship between kindred spirits) cheap and tawdry and can't undo that. I know I have myself to blame for my half of this, I accept that. It just feels lousy, though.