I'm sorry you're going through this. I'm in a similar situation and it sucks...but I'm also seeing good things.
My husband of 10 years moved out 3-4 weeks ago. Our entire relationship he would stay sober around 18 months, relapse for a few, sometimes leave me but then would come back around and we'd try again. I'm sad sometimes. I'm lonely sometimes. I'm also very relieved in some ways and things are simpler and more peaceful.
I do have to steer my thoughts away from the whys? I sometimes suspect there was/is someone else because of the suddenness of his leaving and no overt cause. It's not helpful for me to ask why. It happened. I need to focus on the peace I feel and figuring out why I stayed in that mess for so long.