The federal government can choose whether or not it wants to be reimbursed. Regarding yourself, you can enforce the contact between your ex husband and yourself by filing in federal court to enforce the contract. Recently the Court of Appeals for the Seventh Circuit upheld enforcing such contracts, without even requiring the foreign nation to try to mitigate or reduce the costs by trying to find work.
The above is intended only as general information, and does not constitute legal advice. You must speak with an attorney to discuss your individual case.
Enforcement of an I-864 is entirely at the discretion of the Federal government.
J Charles Ferrari Eng & Nishimura 213.622.2255 The statement above is general in nature and does not constitute legal advice, as not all the facts are known. You should retain an attorney to review all the facts specific to your case in order to receive advise specific to your case. The statement above does not create an attorney/client relationship. Answers on Avvo can only be general ones, as specific answers would require knowledge of all the facts. As such, they may or may not apply to the question.
I agree. The I-864 is not for you to enforce.
FORMER IMMIGRATION LAW PROFESSOR -- LEGAL DISCLAIMER: This answer is offered for informational purposes only. It does not constitute an attorney-client relationship.