Obsessed About Sharing Nude Pics Of My Wife

I am fortunate to be married to a very attractive busty blonde lady who turns heads where ever she goes. She is 10 years my junior, 1'm 60 she is just 50 but she could easily pass for 40.
I have often fantasized about watching her being made to orgasm by other men.
This is NOT something that she is into however. It's been very frustrating at times as her libido is somewhat less than mine, despite our age difference.
I often end up watching porn and getting myself off while she goes off to bed alone....to sleep.
A couple of years ago she told me that she realized that it must be frustrating for me not getting as much sex as I need from her, and as a trade off offered to pose nude for me once a month.
She's not happy about me masturbating to porn and would rather that I get such pleasures from looking at her photos when I masturbate.
So now I have over 2 years worth of photos and a few videos of my lovely wife.
She made me swear that I would be the only one to ever see the pics etc. Of course I agreed.
BUT, like I mentioned earlier, I also fantasize about watching her with another guy.
I showed a good friend of ours some of my wife's pics....in confidence.
Initially he was good about it and we'd sit side by side looking at her pics and videos on my laptop and wank ourselves off.
He's been asking for copies for himself for some time and I emailed him some pics of her.
I knew this was an idiotic move, but I was also turned on by the whole "sharing her" with him.
He's become more demanding recently.
He has said that if I don't do a number of things, he will tell my wife that he has nude pics of her.
One thing is that I am now taking pics of my wife posed to order for him. Having her pose in ways that he wants to see her, not necessarily how I want her to pose.
He also insisted at one of our masturbation sessions that I suck his cock for him. To be honest, at the time I was so aroused by the whole thing, that I did it willingly. Problem is that he videoed me sucking him. Now he has this to use against me.
It get's worse.
He's now persuaded me to allow him access to our bedroom when the wife is out, so he can go through her lingerie drawer AND play with her vibrators.
I know I should have said no, but I find it so hard to say no to him.
I have given him oral sex on many occasions and even posed for photos dressed in my wife's lingerie for him.
I really do enjoy it at the time but am wracked with guilt later.
Now I am enmeshed in this web of deceit I can't think of any way of getting out of it.
I know it's wrong, but I love to share her pics and videos with this man, AND I've become equally obsessed with being his "bitch". I am so eager for our suck sessions.
Every time we get together he takes more pics and videos of me serving him.
Every photo or video of my wife that I take I now automatically copy him in on.
My wife would be furious and ashamed if she knew he had seen her naked, sucking me, being licked to orgasm by me....
It's terrible, but at the same time it give me my sexual release that I am not getting from my wife.
Recently HE has had me anally. I was amazed how much I liked it and how eager I am for more.
I don't think I have a way out. I am in too deep.