Don't even be sorry. I can totally understand where you are going through. I am very sensitive and always doing for others but sometimes it all comes crashing in and it's too much to handle. It's no wonder we shut down. I do the pacing around the house and cleaning, too... it soothes when writing doesn't.
This will pass and your sister will get a place, hopefully sooner than later and you can get back into the groove.
I am here for you, girl!! Message with anything you need. Big hugs <3