T.S.
Hi L.,
I'm sorry you're going through this. My divorce was finalized today (after moving out and filing in 2008! ugh) and I can tell you it DOES get better, and the stress of moving on is nothing compared to the unhappiness I felt staying in an unhealthy relationship.
Most family law attorneys will do a consultation for little or no money.
Child support is pretty easy to file for. Look up your county's family court online. Their website will probably have a list of frequently asked questions and steps you need to follow. If I were you I'd go file for custody and support RIGHT AWAY so that there is some kind of order in place. You can always modify it later to make it more workable for the three of you, but you don't want him running off with your child without any way to make him come back.
As for the lonely and sad feelings, I know it's tough, but you will get through it. If you weren't lonely and sad after deciding to leave the man who fathered your child THAT would be a problem. Are there any mental health services covered by your health insurance? I started seeing a therapist once a week when I moved out and then attended his "relationships adjustment group" which I found SOOOO helpful and strengthening. Another suggestion would be to look for a co-parenting class or a single parenting group. You'll learn some really valuable information AND meet other people who are going through similarly challenging times.
Hope this helps. Good luck to you.
T.