I'm in a similar situation, separated from AH for 6 weeks now, and finally letting myself contemplate the idea of divorce. Our anniversary is tomorrow, and needless to say it's been a really rough weekend for me.
We've been married 13 years, but AH has been in my life for 23 years now, since I was 15 years old. The idea of divorcing him is tearing my heart out. I feel like along with the end of our marriage will be the end of all of my memories, since I was a teenager. We truly did have happy times, and I still miss my best friend and the man he used to be. I still get glimpses of that man from time to time, and it tears me apart to leave him. I'm trying to allow myself to grieve for the death of my hopes and dreams for a happy future with him. He was the love of my life, and alcohol stole that away from us. It's such a tragedy, and I could go crazy if I allow myself to think about all we've lost.
I've found it helped a little to write a list of things I WON'T miss about the marriage. Things like, getting a pit in my stomach every time he doesn't answer his cell phone, being afraid to travel out of town in case he might relapse, subconsciously monitoring him at family functions to make sure he's not drinking, etc. So far my list has 45 items and keeps growing...
Hang in there. This has been the hardest and most painful period of my life, but I know we'll make it out on the other side and there's a peaceful, happy life waiting for us. I just wish I could figure out how to get there....