@Eliusa,
I'm getting the impression now, that this is to do with "age".
You made a comment that you two were friends only for 5 years because you thought he would go for someone younger, yet he at some point started giving you attention and so, you didn't feel so old anymore, more like a teenage girl again.
This is normal. That being, the desire to feel young, the feeling you get of being like a teenager or young woman again, the attention.
BUT, 50 is not old Eliusa. I was married. I walked. My fiancé and I have been together for 5 years this December, finally about to file the Divorce, complicated story. So I was 47 when I met my fiancé not old.
What you don't know is whether he was only a friend, not interested, you pressed a button of some sort that made him think you were interested and bam, this flirting and emotional affair began. What you "think", I think is that in another 5 years you will be 55 and by then, you think you will be too old, he won't want you but your husband has stayed with you all these years so you are "safe" on the age thing, by staying and just seeing, in-case this guy dumps you.
You don't want to be alone.
You're fear is age.
That's why you won't leave.
If I am right, then isn't that using someone? The just in case?
Yet, if I am right you are so wrong. Age is beautiful, embrace it, you've learnt a lot and can still be girly. And, I obviously made sense in something I wrote before because all of a sudden you worried a little, that maybe, your Husband is putting on a false front but actually deep inside, knows he is not being loved at the moment.
I do get the bit about him not taking pills. And, where you are in your prime sexually. And, even though you have made suggestive threats it hasn't worked either.
I get that he probably thinks you'll get over it, he doesn't want sex. Your time together over the years, you won't leave him.
Leave. Tell him that you will go back if he gets help. That intimacy goes hand in hand with bonding, love. That you want the relationship to work but he's holding back and your hands are getting tied.
Sometimes drastic measures can turn into good results.