Is there any deeper reason why you detest your stepfather ?
I am not saying this is the case but, I had for most of my life repressed hate for my father and I did not know way, as I used to see him as a "normal" person I was wrong as he was an abusive father and I wasn't able to remember details, until recently.
Just ask your GD if you are only overreacting, or there is something bigger inside you, that needs to be vented out.