Most people who have long term disability insurance from a private company have signed a contract to repay any past-due Social Security benefits they obtain. It is true that you may have a legal obligation to repay. And the company may be able to get a judgment against you in court if you do not repay. However, Social Security benefits can only be garnished for debts you owe the federal government or for past-due child support. Not for what you owe a private insurance company. So even though there is a judgment against you, they may not be able to get their money. You cannot squeeze blood from a turnip.
One lesson here is DO NOT BELIEVE what the person working for the insurance company tells you. What they say may very well be in the interests of your insurance company, not your interests.