What is the best way to discuss moving my wife's Dad into a home?

You're normal, not selfish! Before I even brought up the subject to my family, I checked out all the places near me. I figured out the math and found a wonderful place (assisted living). They took such good of my mom! She went from laying on the sofa in her robe all day to wanting to get up and brush her hair, getting dressed and sitting instead of laying. It was the best thing I ever did for her. Do your homework first, when you bring up the subject in a vague way, they won't even listen to you and they may even get upset. My mom had such better care, a beautiful apartment, ordered off a menu in a fancy dining room, loved the entertainment and happy hour! She had more visitors and she flourished. The place was my support system, I could not have done it without their help. Good luck to you...

If he would agree to go to assited living I think it would be better for him and your family. Some folks do a great job caring for elders at home till the very end, but it's very hard to balance the demands of caregiving with family life.

I would love to get my folks into assited living but they are very stubborn and won't even discuss it.

More answers here: https://www.agingcare.com/questions/Convincing-My-Wife-time-to-let-her-Dad-who-lives-with-us-move-into-a-Home-186057.htm

No, you are not being selfish. You want what is best for your Dad-in-law, and what is best for you and your wife.

Dad might enjoy being around people of his own age group, dining the common dinning room, making new friends and having new buddies to hang out with. He can still have his TV/Computer.... but he won't be alone during the day, which can turn out to be a really long day and not much to stimulate the brain compared to being around people of his own generation. Gosh, all the things they could talk about.

If Dad-in-law can afford it, why not check out some of the continuing care facilities, as some will provide a free lunch to visitors. See what he thinks about it, he might surprise everyone and say he likes the place. Better for him to move now while he is still able to function, that was he can learn his way around the place and get to bond with the Staff.

That way your wife when she is around him will once again be his "daughter", not his "caregiver".