It forces me to slow down at home, not worry about the holidays or work and focus on myself and my recovery.
This is really the crux of it. Once you get through your recovery, then be deliberate about "I force myself to slow down and (fill in the blank)"
When sis wants something, clarify you have the request right, let her know you will take time soon to focus on her and will be back to her (be deliberate about picking a timeframe that works for YOU)
She will do what she will do. When you do elect to spend time with her, be fully present for her, focus on the now and then when your time is up (that you have thought through ahead of time) move on with your life (no jade or explanations...just do it)
You've got this.
Best wishes on your surgery!
Best,
FF