I'm sorry to hear about your niece. When cancer strikes, the best you can do is be there, to ask what they need... to listen and not to fix. Love, acceptance that she still is the same person she's always been and a positive mental attitude go a long way.
A car flipping over in front of your house? Who are your neighbors, stuntmen? It's good to hear no one was hurt.
I'm working hard to get over the blame game. The more I blame the less positive energy I have for myself and my children. What to do about algebra? Some teachers have the top students tutor others in their class. Kids sometimes can learn better from other kids. Have you asked the teacher for suggestions?
Whether you send an email during the day or at home late at night, it's still communicating with the teacher. Perhaps you and their dad can agree to copy each other on all email from the teacher.
This isn't a question about who's perceived as the better parent but what's best for your son. Plus if you're both struggling to help with the algebra, perhaps a third party would be best.