Maybe I'm completely out of line here...but your sister sounds like a class A BAG! I mean, who does she think she is talking to you in that way! She is obviously self-absorbed, b/c she can't see past herself, to see her mom and her sister need help and guidance! (Sorry if that is totally out of line, but that made me mad!)
As for taking care of your mom, maybe this is your chance to get yourself past some of your own fears. She needs you, and I am sure you want to help, it's just feels like too much. Remeber that you cannot "catch" this, and cleaning her and her bedsheets are not going to cause you to be ill. It just might help you.
If i start to get anxious (when at home), I start to clean, do laundry, change beds, clean toys. Takes my mind off the anxiety, and passes the time HUGE!
You can do this (BIG HUG)!!!
Crystal
That, which does not kill us, makes us stronger!