knows he has a problem but thinks its under control...

[moowens]

My partner of 3 1/2 years ( we have been living together that long also) has had a problem with drink since his teens - he is 44, I am 31. All of his relationships prior to being with me, have ended (from what I can glean) most likely as a result of his drinking.
I had known him casually for many years prior to our hook-up and knew that he had an issue with drink.
Anyway, we fell in love and in every other way we are ridiculously compatible... same life principles, both musicians, both vegetarian cat lovers! The list goes on. In the time that we have been together, he has reduced his drinking dramatically. Trouble is, it still seems to me like he abuses booze and seeks it out more than I find comfortable. Sometimes once a week of a night out, but more often twice weekly. Other times, he is chomping at the bit to get out even more than that. We argue about it consistently.
I have been tender and understanding with him, when he admits to having a problem, but his drinking still ends up hurting me. He is not usually an argumentative drunk, but I do not like to see him drinking to excess repeatedly. He knows how much it upsets me but continues to behave in this way.
We love each other dearly but I don't know where to go from here. Although he has made incredible progress in the time we have been together, I still believe he has a drink problem and he has the capacity to hurt me more than I have ever known. He tells me he is working on it etc but there are times (like right now - after we played a gig together tonight, had a conversation prior to the gig about him keeping an eye on his consumption, knowing we have a lot to do tomorrow, which resulted In him drinking excessively and making a fuss about leaving the pub, even though the cab was waiting, bla bla bla - he just seemed hell bent on getting shit faced...before I came to bed I told him I was leaving him. he is now in spare room.
I don't want to leave him... in many ways he is my rock. My Mum was diagnosed with stage 4 lung cancer 7 months ago and I am struggling to deal with it. I need a reliable, strong partner in my life and although he has been that person for me at times, he is also capable of doing me serious harm in my hour of need. I often wonder if I didn't live in the house that he rents, if we didn't have 2 cats together ( to whom I am fully committed!!!) and if my Mum wasn't ill, whether I would still be with him...
I don't know what to do and would appreciate any help.
M x