Hola hola32!
You pose an interesting problem. I do know that once you have a social security number, it is yours for life. Moving to another country doesn't mean you lose it. But, I don't know if you are not an American Citizen and you are living in another country, whether or not you will still be able to collect on your husband's social security. If he has a pension plan from his job, if you are named the beneficiary, you will receive that. It doesn't matter where you live.
I think the best thing that you can do is to call the Social Security Administration and find out what your options are. All it might take is for you to follow through and get your U.S. Citizenship. If your husband works for the government, you probably should talk to him about your concerns. He could ask someone in his Human Resources Department what you both can do to ensure that you will receive his social security if something should happen to him. In any event, here is the link to the Social Security Administration. At the top of the web page, there is a link to contact them.
Social Security Online