Yez - I so relate to your post. Like some of the others here, I know those moments of complete anger when you are trying to raise a child alone (I have one daughter). Just the other night, she wasnt going to bed and I raised my voice and she said "mommy, don't scream at me". I have never felt so sad (and angry) because sometimes I feel if I had someone to help when my patience was low maybe it would be better for her.
Keep doing what you are doing.
I understand when you feel like everything hits you at once, but as the old 'adage' goes - life/God/your HP doesn't give you what you can not handle.
On the school pickup question - I agree. Do you have sole custody? I haven't read all of your posts so don't know all of the background.