Yes please do take extra care of yourself. This is hard!
I would also recommend that you try to turn your thoughts a bit (I know, again, hard!).
Instead of thinking - 20 years and that's it! Try to think perhaps - we gave it a good shot. I did my best. I really tried. All those things are true too.
Also, he is not dying, he is moving. Who knows, somewhere down the road he may seek recovery, one just doesn't know.
But again, in the meantime, be kind to yourself.