Tone is the use of pitch in language to distinguish lexical or grammatical meaning. Pitch requires sound. You can't have pitch in prose. It's impossible.
You're certainly not pissing me off, quite the opposite really
I think there's some over reacting going on at your house, on both sides of this ordeal, your parents and yourself, but I certainly don't think I'm being a jerk.
The big problem here, is that you feel guilty. Clearly I've struck a cord, but it's not my fault you feel guilty about this. You're reading my text, and applying a tone to your representation of my voice, so however you hear it in your head, is how you think I should be saying it. It's not my fault that you think it should be said in that tone.