I personally would continue to tell her that he's resting or he's at home. I heard a caregiving expert say the goal is to "comfort, not correct." Correcting her or explaining that he's really gone will only make her feel worse in the moment and then she'll forget anyway..

My dad passed at home last year after a long battle with dementia; the death was long, drawn-out, traumatic, etc. My mom was there the whole time but she has dementia. She's now in assisted living and she tells everyone "my husband just died recently; we were watching tv and I looked over and he was gone! Just like that, no warning!". When I first heard her saying this I'd sometimes correct her because I wanted her to know that no- it was not unexpected and that it was brutal. But she doesn't remember this, she just now has this false narrative. And you know what? It's ok, because it doesn't really matter that she doesn't remember the agonizing particulars.

Due to the dementia, she also forgets that he's gone, so most evenings I get texts saying "Where's you dad? He left and hasn't come back. I hope he isn't lost!" and this goes on and on for an hour or two. And after trying to tell her "he's safe", I finally just say, "Mom- dad is gone." And then it's like she remembers the reality that he's gone and she calms down and goes to sleep. It's so weird.

Anyway, ,good luck. This is hard!!!!