Hi, I haven't read through all the threads, just the main original posts and this thread, so sorry if there is some overlap.
Well, the situation is not good in the sense that this is not what you have signed up for when you got married. However, it seems you want to make it work, so you are looking into dealing with a poly relationship. Others had given good comments already, but I wanted to add another perspective.
I think sex being better with a lover can happen easily, even if the guy is not better in bed, the novelty and differentness can add to the experience. The point here I think is not to think who is better, but how you can go to a different level of connection with your wife. Yes, it is very possible that the new guy is better in bed. You will be compared. But you have your unique attributes your wife likes about you, among them the fact that you let her have others in the relationship. So your marriage has this special aspect and intimate connection.
Perhaps there can be stronger bonds if everything is done right. I think it is also okay to let the wife have sex with the bf, and you just have a more mental-emotional kind of relationship. Can you handle that? How about your sex life?
I am also interested in the cuck/hotwife lifestyle, so for me a better lover in bed seems to be a plus. After all, if your wife still loves and wants you despite all the good sex in bed, then you do have a very special relationship. There is also risk involved, of course.
But, again, if you love another woman, but you also in love with your wife, would you think less of your wife because the sex is so much better with the other woman? I wouldn't. I love my wife so I cherish the things we have, and try to understand her insecurities. If it is truly poly, then it does not matter if someone is better. Even if one of them is inferior in every aspect, I would still love her because I love her. Love should not be a utilitarian decision, love should be love. Now, I don't know if your wife thinks this way, but if you are supporting and you are by her side and she feels secure and trusted, then that should move the relationship to a good direction. Jealousy can be dangerous. Either way there is risk, but perhaps you can tell her that you need to stop having sex for a while, but you want to go on dates, or discuss her love life, or be there for her in other ways that also satisfies you.
Ultimately, this is not the marriage you agreed to, so you have to decide. But if you go along, there can also be improvement in your marriage in the midst of all kinds of risks.