My question involves insurance law for the state of: MD

I have a group life insurance policy on myself thru my employer, and also allows me to insure my husband and children if I want to. I chose to also insure husband. After my divorce I did not change my life insurance to remove my husband. He passed away. I received information from the insurance company that I am entitled to receive the insurance payout as long as I am still married. I sent in the death certificate and it was checked divorced at time of death, along with him having a different address than mine. Was the insurance company supposed to pay even though we were divorced? Should the money be returned?