I think part of the problem might be that you're trying to somehow compartmentalize the relationship--you know there were some truly awful parts of it, but you remember happy/good times and it's creating this dissonance in your head.
Alcoholics are not evil people. Nor are they wonderful, but deeply tragic figures. They are complicated people (as we all are), with some great qualities and some qualities that were distorted by their addiction. They are flawed human beings, like the rest of us. The drinking or drug amplifies any character defects to the point where they overshadow any good qualities.
Eventually, my bet is that when you've had some time to grieve and to heal, you'll be able to think back fondly on some of the good times you had without having to counterbalance it with negative memories. I have a lot of fond memories of having fun with my second husband (the one I had to leave after he went back to drinking after almost dying of it). My kids do, too--he was a fun person, very full of life and imagination. The drinking made him impossible to live with. I have no regrets about leaving, and I hate some of the things that drinking did to him, but I don't hate him. I would love to hear that he found sobriety and was living a happy life. I don't think that will ever happen, but for his sake I hope that it does.
So I'd say right now that I have a pretty balanced picture of what our life once was, and can smile at the good parts and feel a touch of sadness about the bad parts, but it doesn't consume me either way.