Liz,
I'm wondering if Robin has always had some of these control and anger issues which have been made worse by the diagnosis and treatment for his cancer. As a Social Worker for 38 years, it has been my experience that when there is any sort of serious Life Crisis we all just become more of whatever our basic personality/ behavior style is - good and bad.
You can't control his attitude but you can give him back his responsibility for HIS OWN BEHAVIOR.
Gary is right- you need to get thru this and that means taking care of yourself. Taking anti depressents, insomnia meds what ever calms you down and gives you some emotional disatance is good.
Your love, support, caring and counseling to him for following the Doctors and other health professional's orders is all you can do.
he is an adult and verbally abusing you which he is doing is not O.K. Amy is right- if your care is not working tell him you will get outside help and do it.

Paula

Caregiver to Gil- dx 11/05. finished treatment 3/06. Stage 4b SCC BOT, rt tonsil, lymph nodes. T2N2M0., 6 weeks chemo, 7weeks daily IRMT. Complete esopoghaus obstruction due to radiation. biweekly esopoghaus dialtions- still on peg tube- so far cancer free.