I feel bad admitting this, but I feel uncomfortable around my mum I think she's crazy.
Why would you feel that way about your mum?
She always talks crap about me to my face.
If you truly think your mother is crazy, you should seek help for her to get her head on straight. If it's just a simple disagreement between you two, just sit down and talk to her so that the lines of communication are open.
You sound like a therapist, I don't need one.
You may not think you need a therapist, and you might be right. But, there are times where telling a professional about a parents behavior can teach you how to talk to your mum in a way that gets her to admit she needs help.