OH my!

You are going "through the mill" aren't you! Now don't compound the problem by drinking again
Do what you know to be the right thing(s) to do. You have made good progress I think, in self care and in trying to rebuild a family. It might take time, and yes, while the children do continue to grow, it's best to build a base for them for the entire future too!
I am glad the chemo is working. Yes, things in life can appear rather small compared to something like that!
Do your best. You can't change all of it. You can do what is right for now, and the future and keep moving on.