@smilie Didn't you recently move into a new location? What would you be able to do that would turn your thoughts away from the hurt you feel with your sister and brother-in-law, and bring more positive feelings to you? Is there a hobby you enjoy doing that would take your mind off the situation? We cannot control the actions of others, but we can work on how we react. I know when my family members have shut me out, I work with the idea that it is their loss that they don't have positive space for me in their lives.
Ginger

Smiliie, you have my sincere thoughts in this time of stress. Remember that we can only change ourselves therefore trying to change or think about outcomes only harms you. If your sister returns home, it possible her husband may reach out to you for assistance with her medical needs as they become more difficult or when she passes. At that time you can see what you want to do. In the meantime, try and think of more pleasant times and going to some short term counseling might help you with your grief. The best to you and your family.

@smilie There is substantial anger mixed with your depressed state, not a place to dwell in if you can help it. The decisions now that you make need to be tempered by reflection on how the future could play out for you and for your family. Perhaps your hope for some reconciliation or resolution to what has turned out to pass with respect to the estrangement you feel from your sister and from the ire that you have over the past.Those are high aims, and maybe you can instead just let things go for a time and see how this is impacting you and those close to you now. Not all things turn out the way we hope, but negative feelings tend to direct us toward ends that we want to avoid but sometimes foster. The more that you stew over this the greater becomes your own distress, and that is hard to think of as being a starting point toward something different than what you fear. You may have to just let it go as it will for now and wait.