First of all, Ur not going to die. I promise :)
This actually happens alot to me. I get into a fight over something wich i know i'm right about. Then i blank out, completely. I also forget what i said before or what i was going to say. I just feel im angry, sad or Hurt. For me it lasts longer then 3 seconds. There is so much i want to say but at the same time im superconfused that what i say doesnt make sense and the other person jumps on those moments. I feel weird cuz of the confusion and think something must be wrong with me (Like u said u think ur having a partial seizure), but i think i partly feel weird too cuz the other person thinks ur babbling nonsense.
Relax and focus on something else completely, i know this is hard. But it really helps. Pick a good movie and some snacks and settle yourself on the couch, for example.
Maybe u got too worked up over the fight or was just tired. It happens to all of us. :)