Hi HopeNYC - NJ here
It sounds like he is struggling, but if you have been reading you already there is nothing you can do for him. Even with sad news of his mom. He may use this as an excuse to relapse. But we know it's just that - an excuse.
We all have to learn how deal with life, the good and the terrible stuff that comes with it.
If he wants to talk about his mom and his feelings of grief and he is sober, you can be his friend if you want. It doesn't have to be all or nothing. But if the drinking and pity party starts - you should back away.
When ending relationships like this, I don't think there always has to be "the big ending relationship discussion" or the need to have closure.
When he checks out - just leave it. Don't call, don't call back, just end it. There doesn't always have to be all kinds hoopla. Just say "I'm done" end of story.
You don't have to feel guilty for wanting a quiet life without an alcoholic. It's actually a good, stable decision.
Stay strong and keep posting