It takes some strength to be honest with yourself and know yourself as a person to do what is best for you. That you feel peace when you are away from the situation is telling -- you are doing what is best for you.
It's painful to contemplate ending a relationship as well as giving up with what we know and are comfortable for an unknown future. Change can be uncomfortable and scary, which is counterintuitive, considering that our lives are constantly changing. I know that trying to hold onto things to avoid change has caused me great pain. When I learnt to accept change it was much easier to let go of the things that caused me pain and to find the joys and blessings in each moment.
Your husband seems to be accepting of his and his family's lifestyle. What you've said is true: you are the one with the problem, you have a problem with his drinking. He's fine with it. What I've learnt from my time on this forum is that when in a relationship with someone, it's impossible to accept them for only part of who they are. If they are an alcoholic / addict, then you have to accept that part of them also. I know that for me, I can't be in any relationship, romantic or even platonic, with an active alcoholic / addict. I simply can't tolerate it, it places risk on my own sobriety and recovery. And I find any substance with which a person alters their consciousness problematic, so I include weed or any other "medicinal" in that category.
It sounds like you are on a path that is most honoring what you need. This is a good thing, no matter how hard it feels right now.