I've just come from your initial post and can understand your hesitation and wondering over this last couple of years.
It can be a very sad thing when a wife after 45 years has to be placed in a home, and if that has left you basically alone in your house it is a lonely way to be, fertile ground for feelings of depression. I'd not think that good for most people. Humans tend to need, and can be happiest, with others.
Do you have a friend you can discuss this matter openly to get your thoughts in order? Trying to decide what to do in isolation is extra hard.
As I don't know all the facts of your circumstances I can only guess. The first thing to say is that if you wish to have another relationship, or sex, to the extent it is constantly on your mind it might be an area to look at seriously.
There are some points worth mentioning. If you visit your wife a lot and she is able to understand , then it might place you in a difficult position if you do seek out another and yet wish to hide that from her. Do you think this might be the case?
The second is that wishing can easily lead to unrealistic ideas, and this can particularly happen if you do not have a life full of other people. While it may be you decide to venture out seeking another, of either gender, things may not work out. If that were the case would you feel better for having tried? It could tun out well but if not would you feel worse than now as a result?
Again the opposite, leading a life of wondering and regret at not having tried too is a horrible way to be.
I'd have to mention finding a sort or long term partner may not be as easy as when you were younger.
So I'm not realy giving you a straight answer to your question, as there are things to consider either way and I don't really know you or all your circumstances.
I suppose the overriding factor is if you are going to remain unhappy as you are, and it does no harm to anyone, then reaching for happiness might be the way to go, even though risky
What do you think?