As the wife of an Alcoholic for 27 years I feel I have to say -
" During his marriage he managed 10 years sober, an unhappy marriage I understand." .
Really? That's what he said was it? It was an unhappy marriage - ? I think after all we go through with our alcoholic partners - the verbal abuse, the cruelty, the unreliability, the emotional neglect - it's not so much that the problem is 'an unhappy marriage' so much as 'an alcoholic spouse.' !! They - the alcoholic are the problem, if he was married for any length of time he most likely sucked all the goodness there was out of his wife and left her broken and hurt. If you can accept that and the fact that people rarely change - I would urge you to read the following
The sticky at the top called classic reading
and then
The Alcoholism and Addictions Help Forums- by SoberRecovery.com (You think that you are so special I)
And if after that you still want to stay with him then keep posting. Sorry if it sounds cruel but alcoholics are liars, so whatever he has told you is probably a lie, and unless he's going to change, nothing really changes.