C.F.
Do it. I went back to school (I'm also a single mom) and I think she learned more about "homework" time. I would study before she woke up and for a bit before my classes after I sent her to school. I couldn't study at night with dinner etc to get going plus I was tired. Get a sitter, use the time to go to the library (away from home) for intense studying time. I met other mothers at school and sometimes we would trade with each other to sit with the kids.
Do it for you. Do it for her. She will see that you are strong and that she will also be strong and maybe even be able to help mom out more. Simple frozen prepared meals go a long way for saving time. Make a huge pan of lasagna, sauce, etc & freeze part. I cooked on sundays for the week. Tiring, yes, but more time at night with my child.
Good luck,
C.