I'm going to tell my mother to go mind her own business
Why would you say that to her?
I get home early every day and I want my privacy.
You can want privacy and say it in a nicer way. Be more respectful to her.
My mom's a bitch who doesn't know when to back up. I'm going to get on her last nerve.
Doing that will only make the problem worse. Just say when you get home that you are tired and need to get some rest. Do not be so rude to her off the jump.