How to tell a parent that you are mentally ill?

Sometimes I feel like I need to tell my mum, that the reason I am like this is because I have BPD. I get so incredibly frustrated with her, and she tuts and says, “here she goes again”. I just want to say for fuck sake mum I can’t help this. My mum is quite a selfish person, what she says goes, if you question her, Its because you are out to get her.
I attempted suicide when I were 21. She came to the hospital to take me home, she never once mentioned it, even to this day, even to ask why.
I once told her I was going to the doctors, she asked why, I told her to get more pills. She asked what pills, I told her for anxiety, she asked why I’m anxious! When I show her my anxiety, she will tell me that I am in a bad mood and that she’ll try to talk to me again n a few days.
This is so frustrating for me.
I had all this this morning with her, I had to self harm because I was so frustrated. Now she is ignoring me and I just want to smash something and smash myself and scream and I can’t handle it. My hands look like I’m arthritic I’m that frustrated. I’m struggling.