Apply for financial aid. If you've already been granted a certain amount, you can apply for more because of your changed circumstances. Also talk to whoever deals with students w/ families or women, etc. Some schools have special programs w/ child care subsidies based on income, or to help you get your textbooks, etc.
Apply for public assistance.
It might be a good idea to find a part time job. Public assistance programs will often provide childcare, but as a student they often want you to work part time, too.
Absolutely document everything, dates he left, lack of money, etc., and see a lawyer or a legal aid organization. Possibly your school might have a legal aid office, mine does. See if they can help you or point you to resources that can.