I'm not going to interact with my dad and grandma
What is your reason for ignoring your dad and your grandma?
I'm tired of hearing their shit about me.
Why are you bottling up all your displeasure? You should take the opportunity to have a good conversation about your feeling instead of avoiding them. It's hard to avoid family so it's better to just rectify the problem and lay everything out on the table or else you will develop anger and depression.
Fuck them. They are stupid losers
If you feel that much hatred towards them you should simply let them know. The longer you hold in all that negativity the worse off you are going to feel. Negativity only weighs you down long term.