I take it, then, that the 3 years has something to do with the length of his apprenticeship and your school plans.
It's noble of you to be so supportive of his career goals. Probably 3 years is not too long to stand by someone who is trying to build a business or learn a trade. However, putting up with alchoholic behavior is another matter., Think of the damage he can do to his body/mind and your heart in that time.
Dino's story has some elements of similarity to your husband's. His parents are not rich, but they certainly had other aspirations for their son than to be a musician. He never got so far as earning those degrees. The irony is that he is really quite gifted as a composer, and had a good foothold in commercial music, but sabotaged himself with drug use.
I too felt guilt about "abandoning" him. He had lost all his friends and my friends were becoming barely civil to him. He only had other losers and me to hang out with. I feared for what would happen to him if I let go. What DID happen, was he finally got some help.
Do you ever watch "the Simpsons". One of my very favorite quotable quotes comes from an episode when "Marge" said to "Lisa".... "Most women will tell you that you're a fool to try and change a man... but those women are QUITTERS!". We laugh at the futility and absurdity of this idea... but a lot of us believe it in our hearts. We don't want to be a quitter.
Your post makes me think that perhaps, though you married your husband knowing where all the warts were, you thought he might change if you gave him a loving environment in which to do so. He didn't, and now you fault yourself, saying that it is you who have changed. I doubt that you really have, except to give up the naive supposition that all toads can become princes if you pucker up hard enough.
He can change. He has to WANT to. You can't love him into it. And where will he find the motivation if he believes his life will go on as usual... he'll be warm, dry, fed and loved... no matter what he does?
Read your posts some more. You have all the info you need. I urge you not to cling to that 3 year plan but to evaluate his behavior on a day to day basis. For recovering addicts and for anons... the magic number is not three. It is one.... one day at a time.
Smoke