Ask your lawyer. Do you have one? If not, get a free consultation and ask (even if you have one, go to a new one for a free consultation so you don't have to pay!) It probably depends on what state you're in. Here I was told even if he doesn't sign, if we are separated for a certain amount of time (even if he is living in the house, even if we have sex during that time...) if we are not living as husband and wife, it counts and the divorce will be awarded whether or not he agrees and signs. You can probably start making your new life now, Just please document everything you can. You will get free and you will be OK. Hang in there for now, freedom is around the corner.

If he wil not sign the divorce papers then this is called a contested divorce, many divorces are contested, it just means that he does not agree with what the divorce agreement is as listed.
So if you can have him agree to something he would sign it? Or he will not sign it because he does not want you to have a divorce? If it is the later you will have to go to a divorce trial, no other option. The judge will hear all of the issues and make rulings on anything that needs to be deceided (marital asset splitting, custody and so forth) once all of the issues are ordered the judge will order the divorce, if he refuses to sign his attorney will sign for him, if his attorney refuses to sign then the judge will order someone to be appointed to sign for him (this person would be a person of your choosing, normally your attorney or relative). It is not the best way to go but it can be done if you have one that wants to fight even for the divorce decree, silly....I had one and it can be done it just takes many court appointments with a judge and a whole lot of money.
See an attorney if indeed this is a contested divorce because there will be more issues than just the lack of a signature.