I'm going to snap at a parent over their comments about my illness
What do they say about your illness?
They just think my illness is lame
Giving in to emotions or frustration, and yelling can increase the intensity of conflict and that is counterproductive. Sit down and talk to your parents in a calm way and let them know your illness is no joke.
Fuck that, I want to hurt them.
If you want to hurt them, then tell them how you feel in a calm and respectful way. Your calmness will make them feel bad more than you snapping at them.