Katrinka, if not already, please contact your local domestic violence shelter. Not only for support and counseling for you and the kids, but b/c they have resources (referrals) that to assist financially. For instance, can refer you to agencies to assist with rent, utilties, groceries, housing, etc. You may have to do the leg work, yet worth it. Also, the shelter may have (or refer) legal assistance/advice. Follow through and do not ever let him in your personal space, home, workplace, etc. If you move, have unlisted phone, number block, do not provide physical address, possible P.O. box if affordable, etc.

Push for child support and if possible, take advantage of the 'dead beat' parent laws (as applicable for your local gov't / state law).

Do not be afraid to accept assistance from others. Here's a link you may find useful:

http://www.womenslaw.org/PA/PA_statutes.htm

Good luck and please keep in touch and ask for any advice/support you may ever need here.