BellaBlue.....You did not do something unforgiveable! As a mother who has been in that position, before---I know that you did the hardest thing a mother can do----and, you did it both him and yourself. I see it as a loving thing for both of you. After all---enabling him harms the both of you, in the big picture.
The biggest job of a parent, as I see it, is to prepare the young to survive in this world after they have reached maturity. This is true for birds and wolves and humans.
If you were not around----what would h e do?
I think that a big fear that drives us parents---especially, in this case, mothers, is this----The fear that our kids will stop loving us and that the rest of the world witl agree with them that we are a "bad parent".
Of course, he is angry. That is to be expected, and, you did know that he would be. (thankfully you did know to expect him to be angry). An alcoholic does not want to hear the word "no"----not ever. They can be very manipulative, also. They will be very sweet and attentive when they are wanting something---and, instantly angry when they don't get exactly what they want and when they want it.
You are going to have to be very strong and hold your line. It isn't easy. When I made the decision to cut my son off from all financial assistance and enabling measures....I actually apologized to mym for having been enabling him. (you should have seen the shock on his face).
You are going to need a lot of support for yourself. Please make sure that you have support from those who really understand alcoholism.