ESA50 enquiry

Good Evening, I have searched thru all the questions and can only find bits to what I need some information too. My husband comes off the CB ESA after the 365 days,at end of April. He enquired as to what he would be be entitled to and was told that as I work 30hours per week and disabled, I have to support him until he reaches 65 in 4years time. He has now received a ESA50 form from Atos, surely if he cannot get the benefit does the form need to be completed. Its bad enough to lose this amount of money, heaven knows what will become of us after next week. But as my husband is a sick man physically and mentally by subjecting him to the most degrading so called medical will only make his health worse. What is the reason for the form?