my wife speaks italian with our bull and i didnt expect to feel like THIS about it

so this is a weird one to type out. we're hotwife dynamic, been doing it about a year, based in edinburgh. our regular bull is a guy who grew up in milan, moved here for work. wife took italian at uni a million years ago and apparently it has come BACK in a big way since they started seeing each other. at first it was a joke. she'd send me a text after seeing him saying something in italian and id google translate it and laugh. then she started using little phrases with me too, terms of endearment that she was clearly picking up from him. fine. cute even. last weekend they were together at ours, i was in the next room as agreed, and i could hear them through the wall and they were talking to each other in italian for what felt like ages. and im sat there with a beer feeling something i havent felt the whole year we've been doing this. like properly hollow. cause heres the thing. she and i dont share a language we dont share with anyone else. we've got our english and thats it. and i suddenly clocked that the two of them have this whole private channel that i literally cannot access without my phone out. and our agreement is that the sex is sex, but is shared language... something else? im 41 shes 38, this aint my first rodeo with jealousy stuff, but this one i didnt see coming and i dont know what to do with it.