It hurts like hell to have to walk away from something that will ruin you, because of someone else's choices (sort of- the choice to seek recovery is a choice; the drinking is a compulsion). It doesn't make any sense, does it?! And its just plain old not fair.
I cry a lot too. But each day I cry a little less. Each time I see him (still married) I find him a little less attractive and begin to find myself a bit more attractive (not a reference to looks) and even though the pain is still there; the uncertainty and fear for what the future holds now, the anger toward him and at myself for believing in him; I am glad I made the choice I did, because I want a real life on my own terms. Not his.
Hang in there. Distract yourself as best you can. Get exercise and sleep (easy to say, harder to do, I know!), and go easy on yourself. You are grieving; its normal.