Bunny, you are doing just fine. Like you, I had to distance myself more and more from my family in early recovery. I couldn't be around them very often. We didn't live in the same city so I mainly had to deal with phone calls and I simply didn't answer or return calls more than once every 2 weeks and I never offered any information about what I was doing. Those things helped me a lot.
I don't think your thoughts about your sister-in-law were 'alcoholic'. I think they were human thoughts. As you begin to get a bit older you start to realize that you won't be able to do all the things you wanted to. That's okay, that's life.