Let me advise 2 things:
1 ) As I read your post, I was reminded of how irritable I was
about 30 years ago. Tho I was polite to others, I got angry
and impatient against myself when I made little mistakes.
A friend suggested that I take something available in healthfood stores
called Pantothenic Acid. When I took this, I calmed down
I was no longer so irritable; of course, it is possible that irritability
can result from other causes.
In retrospect, it seems like I had a mineral deficiency of that.
2 ) If you have found it necessary to defend yourself with a threat
of deadly violence, then it seems that you may need to evacuate
in order to avoid a possible homicide; (you mentioned need of a defensive knife).
Maybe your family (parents ?) can advise you about how to safely get away.
Possibly you might see if the Pantothenic Acid calms him down
before deciding whether to remain with him.
I wish you the best.