I'm going to insult my grandmother
Why do you want to insult your grandmother?
My grandmother patronized me.
I know it's frustrating to be patronized, but you need to behave in a more respectful way toward your grandmother. You are not being kind towards your elders. Your family members will be angry with you if they know how you are treating your grandmother.
My grandmother is a bitch
It's disrespectful to insult your grandmother. If you can't respect her, maybe you should try to limit your interactions?