I'm not going to give my grandma her ex husband's ashes
Why are you not going to give the ashes to your grandma?
I hated her ex husband. I want to throw his ashes in the trash.
You should respect people's wishes after they have died. Your grandma probably really loved him and not giving her his ashes is like depriving her of love.
I won't do what she wants and I'll always remember this.
It sounds really cruel to do what you are planning. You can just hand them to her and never have to deal with them again. Can you imagine what people might say if they found out you threw away someone's cremated ashes?