If your husband's son (presumably from the content of your question not your son) is his financial agent, he may have broad authority. If you have a copy of the power of attorney your husband gave his son review it with an attorney to see what it provides. Many form powers give the agent the right to change ownership of assets (retitle), make gifts, etc. The son could conceivably have the authority to give the car (since it is titled in your husband's name) to himself as a gift!

If you divorce your husband the disposition of the car will depend on the overall settlement and state law. If your husband's paralysis is permanent that will make the process even more difficult for everyone.

You should get copies of all the documents as to the ownership of the car, payments for the car, payments for repairs and insurance, etc. Even if you made car payments if your husband paid for insurance, took care of the repairs, etc. you may have a dispute of who really owns it.

If this is a second marriage for you, did you sign a prenuptial agreement? If so, that needs to be looked at to see what it says about ownership of assets.

A number of points in your question were not clear so we edited them. There are a number of significant facts that seem to be missing. Also we cannot comment on specific state law on this website, only general ideas and information. You should call your county bar association and see if they have a legal help clinic or some other method of helping put you in touch with a lawyer for a reasonable fee in light of the issue you have.