S.C.
You do need a lawyer, unfortunately. There are ways you can do it without one but in your position I wouldn't take the chance. It HAS to be done right, no loopholes, no question marks. As someone said, if you communicate with a women's shelter they may even be able to point you in the right direction to get some help.
When I left my husband (HUGE KUDOS to you by the way for being brave and standing up for the well being of yourself and your kids!) he did the same thing, "I don't care, just show me where to sign."
I did my best to be "fair" (actually I was MUCH more than fair) to him so that he wouldn't throw it in my face later (mistake, by the way, and didn't work anyway, but not relevant now). I hired the lawyer, I filled everything out with his help/advice, and I had the sheriff's department serve my ex with the papers. He signed. I went to court, he didn't show up. Honestly you can do this with VERY little interaction from your husband. At least that's how it worked in Kansas - California may be different - but that's where the lawyer comes in, he can tell you what you need to do. That's his job. Then you know it's all done correctly and no chance for your ex to come back and screw things up later. Good luck - and GOOD JOB. Hang in there!