I recently got engaged to a man who has lives with and has cared for his grandfather for the past 10 years. Is it wrong of me to suggest putting him in a nursing home so my fiancée and I can focus on our marriage and buying a house?

I am new to this site and new to caring for the elderly all together. I feel lost and I need help from anyone who can spare it. I recently got engaged to a man I met on the internet 2 years ago. Although I knew he cared for his grandfather when I met him, I didn't know the details.
His grandfather is an 84 year old widow. I would hate to call him stubborn, but it is one of the best words to describe him. If I was having a bad day I would go as far to say he is lazy, care less and selfish! But I love the old man. My fiancee has been living with, and caring for his grandfather the past 10 years! They are from a broken family so I feel his grandfather relies on him more than usual for that reason alone. My troubles come into play as I am recently graduated college and now have plans to marry and buy a house with my fiancee. But I need to know if I should suggest putting his grandfather into a nursing home. I don't want to come off as the selfish and care less one, or make my fiancee feel like he has to choose between us, but ultimately, I feel he should focus his energy on our relationship and his own interests rather then worrying about his grandpa.
My fiance pays the bills, and then the two of us share the housework, grocery shopping and any and all repairs in his grandpa's home. His grandfathers home is falling apart because he refuses to spend any money for repairs. There is no working shower, running water in the kitchen or working washer or dryer. Luckily there is heat and air conditioning because my fiancee was once a heating and cooling installer and did it himself. Aside from the poor conditions of the home, his grandfather is a real piece of work. He is constantly making a mess; not in one room, but all rooms. Dirty dishes, empty food wrappers, food and drinks spilled and smeared all over the place. Newspapers piled up on tables and furniture. Yarn and tape that he uses for god knows what!
My fiancee also believes his grandfather has stolen personal belongings from him in the past. There is a collection of garbage, stolen junk and cardboard in his room.
His grandfather has poor vision and hearing. He is unable to walk for long periods of time without shortness of breath and pain in his legs and feet due to the fact he spends the entire day just sitting in his chair watching t.v while refusing to see a doctor even when we make the appointments for him. He doesn't even have a family doctor nor will he even hear about us finding him a new one. He believes alka seltzer is the cure for anything. This results in us getting sick from his constant spread of germs as he doesn't practice good hygiene. In fact, he doesn't even use soap. He merely soaks his hands in water whenever he uses the washroom.
Late last year, we had to rush him to the hospital as he had a hernia for so long it became tangled with his intestines. He fought with us about bringing him to the emergency room and refused to allow the hospital staff to come into his home to check on him and help him get back on his feet. He was out of commission for awhile and relied on diapers that we bought and found hidden in his closet. He would make home made diapers out of plastic bags and rags he would find to save money. He refuses to spend a dime on essentials. Tooth brushes, tooth paste, deoderant etc.

Another thing is, he is constantly making up stories about his past, things he sees on t.v and loves to gossip about his family including my fiancee who is his caregiver!!!
Although he is able to remember appointments like the time and day to be ready for grocery shopping, names of his family members, names of television shows and the days and times they run on, I feel if he lived alone his neighbors would complain of an unkept home, loud tv, and mice (from the constant garbage pile up and food being dropped on the floor and such). He cannot make popcorn without burning it, yet he still attempts to cook biscuits and such in his oven. His diet only consists of t.v dinners and pepsi. Again he is 84 and isn't on any medication or diet. I also think he would be in trouble for not paying his bills as I already stated, my fiance has been paying all the bills for the last 10 years. Of, course, we would still take him grocery shopping anc maintain his yard, but we would no longer be doing his housework or helping him care for his dog.
I guess my big fear is my fiancee and I getting in trouble as some people may see his current lifestyle being a result of neglect. The social worker from the hospital questioned his home made diapers and the untidy home that the paramedics reported to be "gross". We try our hardest to clean EVERYDAY. To put food in the house that can be cooked, and he refuses to eat with us. He will not see a doctor and we are told we cannot force him even when it affects our health. I am also worried my fiancee will feel to guilty to move out and start his own life with me and let his grandpa finish his life the way he chooses..