I just couldn't "like" your first post. I can 'hear' the disappointment and hurt in what you say.
And I understand them; I've felt that same hurt and disappointment from every woman I've been married to. It's quite humiliating as it is, and becomes moreso if they are aggressive about rubbing your nose in it.
I don't wish to be presumptuous, but if I may offer some advice....learn to enjoy it. I did. It's obvious she's not going to stop, and you must love her to still be married to her, so be proud you have a GREAT slut wife!
To my eyes, she looks like a perfect slut, and if she were my wife, I'd want her to fuck other men, too! Of course, I wouldn't want her to 'cheat' every single time. I don't know what you think about watching her fuck, but I would want to watch her every time I could. I also would think she would have some desire for you to watch, at least on some level. If she enjoys the humiliating aspects, that would be the perfect time to do it!
So I hope you can at least reach some common ground with her if you have any desire to watch/participate.
In the meantime, convince her to "teach" you how to become a more proficient lover. You can absolutely do the best with what you have to work with, so train hard. I'd think oral skills would be the best place to start, so do what you need to do to learn new techniques, and practice, practice, practice. As you become more skilled, you can start to work on your cock, and learn what you CAN do with it. Repeat practicing new techniques.
You likely won't ever satisfy her to a point she stops fucking other guys, but there's no reason she can't enjoy having sex with you as much as anyone. Maybe even to the point she spends a bit more time at home.....