How can I get my father to understand that mom's care is his responsibility too?

My mother is disabled and has lived with me for three years. She has been in and out of the hospital several times and currently is in a rehab facility for a recent hip surgery. The co-pay just for this rehab stay is $1,700. I am responsible for ALL of her care. I have a sister who lives 1,500 miles away. She does not contribute financially. My parents divorced about 20 years ago. My dad lives close by and we stay in touch. He knnows the stress I face - working professional with a full-time (50hr week) job, taking care of mom, etc. He has NEVER offered to help financially. He alwasy tells me that I should just "put her in a nursing home." In my opinion, if it wasn't for my FATHER, then I would never have been BORN! So - I think he should be helping out because - even though he may not want to help HER out -- he should help ME out - instead of offering useless advice. He has money - he has a lot of money. He's very tight. He has a girlfriend and they may get married. I'm excited for him, but I NEED HIS HELP. Does anyone have suggestions as to HOW I get him to understand that SHE IS HIS responsibility, too?