I understand your situation, it can be very spirit crushing to go through this.
His drinking might be due to depression... it can be very hard for a man to speak to a Dr about intimate matters, but it may be a hormonal thing such as low testosterone, something that the Dr can do something about. Not only can low testosterone cause low sex drive, but it can also cause depression, tired feelings, aches and pains and a slew of other things that do not help in the sex drive department. Talking to a Dr and having a few simple blood tests can be very freeing to him... it is not admitting he has a problem, it is taking control.
It is also normal to feel resentment and to build walls to 'protect yourself' because you wonder "is it me? what did I do wrong?" and that can lead to doubts about how you feel about the R.
Have you read the first chapter of SSM? You can read it online from this forum... it really pegs how the SS partner feels and gives a wonderful look at the partner's perspective... something that I just recently did myself and it helped me to understand a little more.
I am afraid that I am just starting out on trying to save my R with what I learn here... what I tried to do on my own did not work and I have a long way to go, but there are many here who have managed to tame to SSM beast and I am sure that they will soon post and share their thoughts and suggestions.
Keep up the hope. my situation is a little like yours, but there are also EA issues in mine, but even though I feel hopeless I am not willing to stop fighting for what I know could be.
M- 11 y H- 40 Me- 41 D (1st M) 19 S (1st M) 17 First EA (w/OOW)discovered 2000 Third EA (w/OOW & phone) discovered 02/06 SSM (total) 3 1/2 years
