Laugh so hard it would sting

Is it normal that when you get scolded you want to laugh in the person's face? I don't know but I did wanna laugh in my mom's face when she was scolding me.
You see we had an argument because I didn't wanna walk the dog and I pretty much win because my sister end up doing it for me. After that she told me that could not use my computer, which was a low blow 'cause she knows how much I love my computer. I stayed like half an hour in my room doing nothing, then I decided I wanted a shower so I went to the bathroom. I suddenly thought in everything she said and feel depressed so I grabbed my razor and started cutting. I didn't do it too much compared to other times. After my shower I went to my computer like if nothing had happened and I wasn't surprised when she didn't tell me anything but all the great plans have flaws, in this case I left my razor in the sink and she found it.
She came and interrupt my reading of the funniest fic, just to tell me that if I wanted to kill myself just do it and finish it all already, she told me that she would send me to live with my father, but I know she won't, I know her she's way too proud to do that. She has know that I self injure for quite a long time now, she only has screamed me about it like 3 times 'cause I'm always careful when I do it so she wouldn't see me or notice the scars. Well she said that she would tell everybody what I was doing and that everyone would know how bad of a daughter I am, that she didn't deserve what I was doing to MY body.
She said she would tell my dad, my teachers, my aunts and everybody. I live in a small community so this would be a big deal. I honestly don't care. I wanted to scream in her face "why? why does it matter? You can tell them, I don't care, it's not like if they are gonna do anything".
I contained myself, I just wanted her to finished her little talk and let me alone to keep reading. After she was done, I put on a really loud song and laugh like crazy at her little speech. I found it hilarious. I know that all her threats are empty she's way too proud to do anything and let anyone think she's a bad mother.
I guess that's all. It was really amusing, at least for me.