>>...He feels I have never really complained about the drinking and that he thought up until two months ago we had the perfect life. It is hard and I feel so guilty because he is right. I hadn't complained much and when I did complain I played it down...<<
Well, now he knows. And he knows how serious it is. What's he going to do about it?
You are being diverted into issues of fairness (you didn't tell him about your unhappiness the 'right' way and on a time schedule he approves of) and feeling guilty for something you have no need to feel guilty about, rather than focus on what is right for you and your children and standing your ground. This diversion is weaking your resolve with guilt and blameshifting instead of fortifying it by placing the impetus on him to take life altering steps to change his behavior NOW.
Well, he knows how you feel now. He knows how serious it is now. The call is 100% in his court.
You say it doesn't feel right to lose an investment of 10 years. Do you want to keep trying and throw away an investment of 15 or 20 years?
Move in the direction that works best for you, and challenge him to keep up (in sobriety) or find his own path in life.
Best of luck to you.