Bravo for exploring your feelings and being able to express them so well here. Pretty damn good, for a bloke!
I love the book Sex at Dawn
Also, you really made me giggle at the idea mono sex is old "bangers and mash." Let's mash ourselves together and bang!
So, anyway, enough with the funny stuff. Like you, when I was married and mono I always craved sex with others. Since I am bi, it was both men and women. I had an uncontrollable roving eye. Sometimes I'd do some mild flirting, nothing serious. I'd get strong crushes tho, on friends, neighbors, celebrities. It did get obsessive at times.
After 10 years together, my h and I had 3 children and my sex drive went away when the kids were little, from overwork, lactation, and sleep deprivation, but once the youngest turned 4, it came back full force and so did my crushing. My husband, like yours, was always extremely jealous, plus he always resented somehow the knowledge that I was bi, which I had never hidden.
I tried to hide my sexual desires for others. (I also desired emotional closeness, maybe that's a girl thing.) But the husband always picked up on it... his extreme jealousy (caused by low self esteem) caused him to have radar for my feelings and desires.
So... somehow at the point my kids were ages 5, 8 and 10, my husband finally began to understand and accept my bisexuality. Suddenly he had an epiphany! If I wanted a woman, he and I could have a 3way. It was a longterm deeply buried fantasy of his. How it all worked out, I won't go into right now.
Also, me being accepted as bi and poly was so freeing. Before that, he'd tried to control my sexuality in many ways, mostly by trying to set a "pure" example, denying he ever felt attracted to another woman ever, denying he masturbated (lying on both counts). Once, he even told me one of the reasons he wanted to move from downtown Boston and buy a house in the suburbs was to take me away from attractive men, isolate me. (heh, of course that backfired because I am bi and joined a womens' support group. :P ) This controlling behavior resulted in me feeling evil, while he was pure.
So, even though our try at a triad didn't work out, and eventually husband and I split (for various reasons), despite counseling... I just wanted to let you know, you are definitely NOT alone in your sexual desires for others. And unlike Mono (who is prejudiced) and opalescent, who warns of a deeper issue other than sexual desire, I feel right in your wavelength. And I want to say, being open about your deep need with your wife is the only way to go. Unspoken needs, denied and repressed, lead to less and less intimacy in a couple. And in your case, even worse, lack of quality of life in many ways.
I suggest you keep talking, and tell her you need to be honest, even if she gets mad, hurt, pissy... she will feel jealous, she will fear losing you... But your very quality of life is at stake. It's great you respect her enough to not just cheat, after all!
Just don't have your discussions in front of your kids!! Seek counseling if you need a private place to talk and a disinterested 3rd party. Read threads here... so many have gone through what you are.
Good luck, hon.