Awwww, sweetie!
I'm so sorry you're feeling like that, it's very sucky! I can feel it right through your writing (don't worry, that's alright). That you took in stride the car key thing? You are seriously amazing. Volatile/overloaded/irritated is familiar turf to me, and well, let's just say it would've gone very differently had I been faced with the same situation(!) With all of everything else going on, be sure to give yourself big time credit for that, ok?
Are you at home or visiting? (Saying you missed your sister made me wonder if you were visiting her or she you.)