We are not aware of a South Carolina insurance law or any other law in SC that would lower bodily injury limits due to being a household member or spouse. You and your husband may want to read again through the policy and speak to the insurance company representative that gave you this information to see what law they were referring to.
It could be that your policy has $25,000 PIP coverage versus $100,000 bodily injury liability coverage and the insurance claims adjuster was referring to the fact your claim would go under PIP and not BI. This does not sound like a liability claim since it was your husband's vehicle and BI normally only covers those that you harm that are not in your vehicle. To cover you and passengers in your vehicle you typically need coverages such as PIP or Medical Payments (MP)
If the insurance company cannot answer your questions or you still need clarification about what coverages you have to place a claim under for your injuries and lost wages contact the South Carolina Department of Insurance. They should have a consumer help section that you can contact about your concerns and claim questions.