Kathy, tell your sister straight away. I was watching my mother-in-law's beloved poodle. she was sleeping on the couch in our bedroom, my 25 yr daughter and I were up and about starting our day. We heard ginger let out a loud yelp. by the time we both reached my bedroom and the couch she was laying on she was dead!
SHE WAS JUST SLEEPING!!!!
Did I feel terrible? OF COURSE! Was I at fault? no how could I be. She happened to have a heart attack and died. IT was instant.
I called my mother in law later that day after we got the dog to the vet. and got things settled at home. She took it very hard. ( who wouldn't) but it was best to let her know the day it happened. She was able to prepare herself emotionally to return home to no dog.
Give your sister that opportunity as well. she needs that time.
Maybe you can offer to buy her another yorkie and the 2 of you can pick it out together.
Things happen for a reason. Allow this to bring you even closer with your sister.
I am so sorry you are going through this. My prayers go out to you and your sis.
BLessings>>> and may the little furbaby R.I.P.