NJ doesn't have legal separations so there are two options.
You can, if your husband is willing, file a separation agreement with the court; while this isn't technically a legal separation it can put in place temporary orders while you decide what to do next.
Or, you can simply file for divorce, request exclusive use of the marital home and temporary custody of your child while the divorce is pending; you can also request temp child support.
take a look here
and divorce forms are here
Again, you have a lot of reading to do, and you may need to click around on the NJ forms site a little. But educating yourself as to how all of this works is absolutely to your benefit!

