I'm so sorry you are going through this!
FIL passed just after Thanksgiving... While the actual timing was unexpected, FIL had been in ICU 2 years ago, so we had started preparing DD at that time. She was almost 9 when the ICU happened, and 10y9m when FIL died.
As far as preparing her, we explained that when people grow old, their bodies stop working as well, and when that happens, sometimes things that we need to live stop working. So, in FIL's case, he had been alive a long time, and smoking a long time, so his lungs were having a hard time working anymore, which is why he had to go to the hospital... and eventually what led to his passing. She accepted this reasonably well, however, my mom had passed when DD was 3yo, so she was already aware that people don't live forever, and that our bodies give out eventually.
We took DD with us everywhere. In fact, she was there at the house after FIL died, when we were talking with the medical examiner. It wasn't ideal, but it was life. She managed better than we expected! So, in the end, she was there at the house until the funeral home arrived (when we made her go with her older sisters over to our house up the street, as we didn't want older DDs there either when they were talking FIL's body), then went to the funeral home with us to make the arrangements, helped us plan the funeral with the priest, went to the funeral (including ahead of time, when the Patriot Riders rode with FIL's ashes), and then to the meal afterward. She was one of 3 kids at the funeral (her, her cousin, and our grandson/FIL's great-grandson who was still a newborn). Many people commented on how much they liked seeing DD and the other 2 kids at the funeral.
DD doesn't seem any worse for wear for being there through all of it. She understood it's just how life goes. And while DD is *definitely* anxiety-prone, we just discussed how it was a part of life, and she seemed to actually took it in surprising stride!
--Mimi
Mom to Lala (2004), Bonus Mom to Big Sis 1 (1991) and Big Sis 2 (1992)
Grammy to Big Kindy Kid (2011), Big Pre-K Kid (2012),
Grandbaby Appendage (2014), and New Baby Grandboy (summer 2017)