It's not too late, time-wise, but you would have to show a substantial change in circumstances of either you or your ex that could not have been contemplated at the time of the divorce. That might be where you would run into trouble. You could easily have figured out that your boys would grow up and go out on their own.
Your retirement fund was probably eligible to be divided with her anyway, due to the ERISA law, which dictates that retirement accounts are to be divided if the parties divorce. This is without regard to where or not your children are grown or not.
To sum up, I think you would have trouble getting the divorce modified due to circumstances. But, it is possible.
If this is written up with the specifics, and signed by the judge, then if the 20% is not going to the sons as ordered, she could be held in contempt of court for willful disregard of a court order.
She can be looking at jail time. Make sure before you get into this, that the 20% specifically is mentioned to be paid to the boys.
DISCLAIMER: Answers from Experts on JustAnswer are not substitutes for the advice of an attorney. JustAnswer is a public forum and questions and responses are not private or confidential or protected by the attorney-client privilege. The Expert above is not your attorney, and the response above is not legal advice. You should not read this response to propose specific action or address specific circumstances, but only to give you a sense of general principles of law that might affect the situation you describe. Application of these general principles to particular circumstances must be done by a lawyer who has spoken with you in confidence, learned all relevant information, and explored various options. Before acting on these general principles, you should hire a lawyer licensed to practice law in the jurisdiction to which your question pertains.
The responses above are from individual Experts, not JustAnswer. The site and services are provided “as is”. To view the verified credential of an Expert, click on the “Verified” symbol in the Expert’s profile. This site is not for emergency questions which should be directed immediately by telephone or in-person to qualified professionals. Please carefully read the Terms of Service (last updated February 8, 2012).