Can UNUM characterize my deceased husband's retirement income as overpayment to cut MY benefits?

I’ve received full LTD income from UNUM for years. In May of 2011, my husband passed and I began receiving his retirement for my daughter who was in college. It was income deemed for her. This month, August 29th, without notice, my UNUM was cut in half. The bank verified that the reduced amount was the amount issued by UNUM. I immediately created an online account with UNUM, as this is the weekend and the office is closed. Once logged on, I saw that my Disability had been reduced $900 due to alleged overpayments resulting from the retirement benefits received from my deceased husband. UNUM characterized this as my retirement. However, this is not MY retirement but benefits from my deceased husband, meant for my daughter whom is out of state for school. I did not realize, that income would affect my disability, as I worked 17 yrs and paid into it. UNUM is giving me a percentage of MY earned income, not my deceased husband’s retirement, meant for his daughter’s schooling and security. I don’t know what to do or how I will survive. They say that I owe them $50,000 in back payment. I can no longer pay my rent beginning Sept., with no warning. I never dreamed I’d be in this position. Will UNUM now grab MY personal small pension when I apply for it in a few yrs.? :'( My God. I am not well. Is there anything I can do?