Your sis in law is MY sister! Stands up to take control in public when she wants to look good, or if she thinks the will may come into play, but close the door and she flops back in the chair and sticks her hand out. No teeth, tatooed, stinks of an ashtray, hasnt washed her hair in days, no clean clothes to her name, and yet screams how its HER that takes care of that old woman, its HER that will be in charge of things when she is gone. UGH! you can HAVE IT ALL! Just step away from her while she is alive. You are really not helping! So, I know exactly what you are saying.
Can you visit during off or less than peak hours? Early AM is a good time to avoid the lazy bones. This gives you time when things are quiet and calm around the hospital. Dinner time is an awful time because of how many show up then, and how many orders get changed during the day.
You have worked really hard with her, and in-law or not, its YOU that has shown up day or night, sick or well, and you dont need to prove yourself to the likes of her or anyone else.
Hang in there.