You actually seem to have strong submissive desires. You don't just want your girlfriend to sleep with another man; you seem to want to be submissive, and perhaps you want to go quite far down this path.
This means that it's a huge change in your behavior!
Some men, when they move towards this lifestyle, are content with wanting their wife to be with another partner. This brings about certain changes, especially in the dynamics of the couple, but the man's personality doesn't change much.
However, in your case, you're going from a man whose behavior corresponds to societal norms to a submissive man. This means that in your case, there's a significant change in behavior and personality, and above all, a change that doesn't correspond at all to societal norms! That's why your ego has been so severely affected.
And this change is so enormous for you that you need to take the time to manage it. Everyone has their own personality: some accept their submissions quickly, others take longer. You need time!
And what happened for you is that things moved too fast! Too fast for your own pace! For someone else, it might have been manageable, but not for you!
So you would have needed things to move more slowly, but since it moved too fast, you couldn't take it all in. And that shook you, destabilized you, and made you depressed.
So you have a desire to continue on this path, but gradually, while you adjust to your new personality.
That's why you wrote this:
What you said seems contradictory, but in fact it's completely normal. You say that "you don't want this," because the way things have been done up to now, it's gone too fast.I think during our conversation last night, I made it clear to her, in a confused way, that I didn't want this, but that I wouldn't ask her to stop either, which she seemed to understand.
And it's this speed that you don't want.
And then you say that "you don't want to stop either" because you'd like to continue on this path, but more slowly and gradually.
So your problem seems pretty simple: you want to go this way, but slower. If it goes too fast, it will freak you out.
If my theory is correct I think you should talk to your girlfriend about it so you can start a transformation process for yourself, step by step, until you are a submissive cuckold.
( Quick note: I feel like you have a girlfriend who really loves you, and is very understanding of your fantasies, and very open-minded. If you really want to experiment with the cuckold lifestyle, I feel like she is a precious woman you have in your hands. )
