If you're in the US, you might look into an in-home respite care program. It's designed to give primary caregivers a break to take care of themselves, get out of the house, accomplish other tasks, etc.

It sounds like there is an overwhelming amount on your plate right now. Cut yourself some slack on not being the ideal caregiver - none of us can sustain perfection for long. You're setting yourself up for failure if you're expecting yourself to be perfect. It sounds like you need a break, and you're not getting one. I would be edgy/irritable/angry in that situation, too.

I think people (especially those with some sort of MI) view all their actions, reactions and behaviors through the lens of their mental state - solely as a reflection of who they are. I think often, and particularly in your scenario, our actions, reactions and behaviors can also a be pretty good indication of the circumstances in which we find ourselves. (I.e., you're reacting in an overwhelmed manner, because your circumstances right now are overwhelming. You're not reacting that way because of your BP, necessarily.)

Good luck - I hope you can carve out some time and space for yourself.