Oh god please don't do this. You will absolutely destroy any hope of a relationship with his wife and not necessarily be in a better position.
You need to have a proper conversation with his wife. Find out what support they have at the moment and what might be helpful for them.
She might not feel ready to think about care homes yet even if you think it's a good idea. He might not even meet the criteria for a care home if he can manage a fair amount independently. He might have said he doesn't want to go and might have enough capacity you can't force him.
She might let him leave the house because that is the safest thing for him, it might prevent him getting distressed and risking violence. There could be options such as trackers if needed.
She might have CMHT input who are already looking at the risks and seeing what is the safest thing for them both.
There are lots of mights here because it is a complex situation with lots of unknowns. You don't have any "rights" to know anything about his care unless he has told his care team he wants you to know (or you hold POA).
Honestly the best thing to do is talk to his wife, ask her what they both want instead of telling her what you think should happen and listen to what she tells you. His best interests needs to be what he would want for himself if he was well and had capacity not what you (or others) think is best for him.