Mfm threesomes in a relationship

Right, here go’s. husband here. I want mainly women and couples opinions on my current situation.
In our 30s, we’ve been together ten years.
A long time ago, I began to have strong feelings and fantasies about having mfm threesomes with my wife. Nothin gay. Just her being pleasures by myself and one other, in a variety of ways. We’ve always had a good sex life and I’ve always felt very attracted to her.
I’m not sure where these feelings came from and why, but eventually I expressed my feelings to her and she responded by saying that she accepts how I feel as a fantasy but it will not happen in real life because it is not something she wants to do and feels isn’t part of a relationship.
Since then, our forpelay and sex has progressively included the scenario of an mfm threesome in loads of ways and we both really enjoy it. We use a variety of toys and she likes to watch mfm porn together sometimes.
In this time, my feelings of actually doing anything his have increased and I’m left feeling unsure about why I feel like this and I hybi cant l ave it go and just enjoy playing with my wife.
I’m still uncertain as to whether or not she actually wants t do it for real, because sometimes, she really enjoys acting out the scenario and has some great orgasms that way.
I feel now like it’s somethjngthats hanging over us because w be taken it as far as we can without actually doing it!
Where should I go from here?! Would it be a mistake to actually ask her if she will do it with me for real? Will I enjoy it as much as the fantasy?
Help?