I am divorced and the sole beneficiary of the life ins

I am divorced and the sole beneficary of the life insurance policy of my exhusband. Am I entitled to receive the funds?My exhusband and I were married for 59 yrs. but had to divorce due to his alzheimers and drinking I am 5 yrs. older than him almost 90 and very frail I could no longer take care of him. We divorced so I would not be legally liable for him. The Probate court deemed him incapacitated he became a ward of the probate court and an estate attorney was in charge of his part of the estate. He recently expired and I sent the Life Ins. Co. his death certificate and they sent me the check. His will can not be found so my daughter produced a copy of a will that he and I made 20 some yrs. prior to our divorce. One of the heirs is contesting the fact that I received the Insurance Monies since we were divorced. Am I entitled to the Insurance money since I was listed as the Sole Beneficiary some 60 yrs. ago even though i had to divorce him? Isn't the Insurance monies a non probate issue or is it part of his estate once he is deceased? Bottom line am I going to be able to keep this money that the insurance company awarded me?