How can I get someone to sign the divorce papers?

My wife won't sign the divorce papers. I agree to give her full custody of the kids. She is violent toward me. I got a threatening voicemail from her. She told my lawyer she won't sign until she gets child support for the second child. Well I don't think the second child is mine because she left me at home alone and she stayed over at her mom's house for weeks at a time and came back pregnant. She stalks me and my attorney says he can't make her sign the paper and it has been 90 days and more. We are supposed to go to court but my attorney wants $1,750 dollars more.