Lilly,
Thanks for the smile. Boy did you hit Katie's button! That is the most I have seen here write in one posting.
I wasn't sure I was going to survive my daughter either. She is going to be five in a couple of weeks and her behavior has improved significantly. We used to battle over snacks (me saying no...dinner is in ten minutes) and shopping used to be bad when I would tell her no (we left halfway through the weekly shopping a couple of times and then sat in the car for 15 minutes while she had a meltdown...couldn't get her into the carseat). My daughter is an absolute delight now and so loving.
It does get better.
If you can get a friend or family member to take her for a few hours on the weekend so you can rest, I recommend you do it.
Hang in there.
Mendy