Is my wife cheating or am i overthinking it?

I am a 38 M.

Something weird is going on in my marriage and want to know others view.

I have been married for about 10 years and about 6 months ago my wife said that she's interested in having a third person join us in the bedroom.

She works in a IT company and said she has a gay friend who found me attractive and they are close and so she wants him to join us. Initially I was reluctant, but after sometime I gave in.

We had some threesome over the last few months, and towards the start it was always me fucking her office friend while my wife masturbated while watching us. However over the last few months, started after a drunken occasion, her friend has now been topping me while my wife watches. She begged me to be the bottom and said it was her fantasy and so I agreed.

But now I am constantly worrying that if this guy also tops then has he ever fucked my wife? I have asked her but she says no, but im not convinced.

Should I stop worrying or is there somethingto it?

As for sex with my wife, I am having that also frequently with my wife and the threesome are one a week sort.