My husband and I are divorcing, and have agreed to sign an opting-out stipulation, rather than drag this through court. It is dirty because he was very abusive. His attorney insists that I sign first, but my lawyer and I think they are up to something.

There is a monetary sum due to me upon both parties signing the agreement, and then an equal sum upon finalizing of the divorce. If I sign, he can hold onto those papers forever. I am worried that he is trying to get out of paying me.

Any advice?

Attorneys are Officers of the Court. There is no reason for the other attorney to "pull something" as the attorney would have to answer to the Judge presiding in the case be informed that hubby didn't sign his paperwork after you signed.

Will slightly disagree, divorce court and divorce attornes fight very dirty and use ever legal "trick" in the book.

Merely demand that it be done at the same time ( like a house closing) if you are to receive money at the signing, they have a check ready at that time.
If not you are requre a third party escrow account be used to secure and hold the money till they receive the document signed and release the funds when they receive the document

... His attorney insists that I sign first, but my lawyer and I think they are up to something. ...

I don't know what hey would gain by having you sign it and then not signing it himself. You realize, of course, that neither of you are obligated to sign?

If you think it may be a trap, include the language that your signature will have no force or effect unless signed by the other party within three days of your signature.

My husband and I are divorcing, and have agreed to sign an opting-out stipulation, rather than drag this through court. It is dirty because he was very abusive. His attorney insists that I sign first, but my lawyer and I think they are up to something.

There is a monetary sum due to me upon both parties signing the agreement, and then an equal sum upon finalizing of the divorce. If I sign, he can hold onto those papers forever. I am worried that he is trying to get out of paying me.

Any advice?

My issue with this is that you have an attorney and still don't have a solid answer. What exactly does your lawyer think your ex and his attorney are "up to"? Why don't you have your attorney draft the agreement if there's such an issue of distrust?

If the agreement states that your ex is to repay you and the judge approves the agreement, then your ex has to repay you - there's no "getting out" of it.