I have been married for 7 years. We have one child together and he has a child from a previous marriage.My husband packed up his stuff and moved out two weeks ago. I DO NOT want a divorce. He says he just wasn't happy.I am on permanent disability. I receive social security. He tells me that I am now responsible for the household bills. I can't do this with the amount I receive from Social Security. Not sure what to do at this point.

First you may not have a choice about divorce if he files for it first. Next if not a divorce you need a legal separation if he is not coming back to protect yourself.

You file for custody of the child ( yours) his other child I will assume is with their mother ?

But you file for custody and child support, Besides that you will have to find a way to pay the bills, or move to some place where you can.

In a divorce you may get alimony but if you are not divorcing that is not a option

Talk to an attorney. He can't just abandon you. If you don't want a divorce, you can try for a separation as Chuck suggests with temporary support.