Don’t worry about definitions. Be you and if your unique, you won’t fit into normal definitions. Gay or bi have generally defined sexual or even relationship preferences. If you only want to play w a cock in this scenario, does that make you gay? Who cares! It means you & your wife have a great relationship filled w trust and exploration.
New sexual scenarios are exciting. It’s funny, my swinger wife has started many play dates w FF play, but no one would ever call her a lesbian or even bi. It’s a fun and pleasurable experience and that is all. She can’t wait to be fucked. The other is just curious exploration.
Enjoy your experience w your wife.