Sister has worsening dementia; any suggestions on how to help her?

My sister has worsening dementia and has recently been told to stop driving and is not paying her bills. At present, she is able to live independently with frequent check ins by her children and myself. The big issue is her husband. He made himself bedbound several years ago and is total care. He is 81 and she is 76. He weighs at least 100# more than her, total incontinence requires her to push and pull on him all the time. She has had multiple recent hospitalizations for extreme high blood pressure, garbled speech, seizure activity. She has consented to putting him in a nursing home but he threatens suicide if she does. Nursing home told me he has to consent to be admitted, is this true? In past 6 months she has declined greatly physically and mentally. Any suggestions on how to help her? He refuses home health and I am working to get a handle on her bills but she is less than willing for that to happen. I plan to force this issue. Thanks for your help.