If she only recently passed away, why on earth would you share with her (I'm assuming not yours?) children the horrible stuff she has said about them? They either already knew, or they had zero reason to know as she is dead and not able to hurt them.

On the other hand, you've decided to throw salt on to open wounds either by reminding them about the sort of mother they had, or through an odd kind of torture through informing them how horrible she was.

They've had her in their lives since they were born. They know their experience with her because that's the relationship between her and them. Maybe it was horrific and they never noticed, but it was the relationship they had with her. They are likely quite upset that you are trying to ruin that relationship.