Long time lurker, first time poster. Sorry about formatting, on mobile. 
I wanted to get something off my chest. I get straight to the skinny of it. I pay the bills my spouse does not and has never been involved in it. That being said i saw a reoccurring number on the statement being that it was right around my number i was genuinely curious. Cause it's as if my calls were being cut short to call this number. I jot it in my phone and do a deep dive search. Its a bunch of text and calls spanning back various months. I don't know this number. Its not in my phone.. fine i dont have to have all the numbers my spouse has. My problem is when i look for this number on the other spouse's phone it has no history just a name.  I confront and get that this a friend of the opposition sex and i wasn't told because of how I'd react.  I'm not a jealous person nor have i ever exhibited such behaviors. This number and my spouse always talk when Im not around. I was told by my spouse that this is an old friend, that is just for talking like for mental health and such. Aita for omission of truth on their behalf. Am i aita for reacting. I can clarify anything in the comments