Ok where to start, I'll do it basically if that's ok as I'm no professional in this area, but so many things jump out a t me.
Ok he is selfish sexually and as you say, he is kind of basically using you as some porn actress whom is there to plaese him. It's an issue that it's all the time and he is just "using" you like an object.
But be wary of a man who tells you he had an evil ex, they were in sepereate rooms, it was all terrible, she was this, that and the other. Truthfully you only have his word about that. I'd be even more wary as she is dead, and can't prove him wrong can she?
He has his own anxiety problems, why is this? So took viagra. Not a huge issue, many keep it secret, or whatever, but in this situation, it just adds more.
He has mood swings and stonewalls you. That's the non-communication.
Then what do you mean by widower issues?
Honestly? He just dosen't sound very nice full stop. Whethet that's him in general, because he lost his wife whatever. The sex issue is just one of many symptoms of his problem.