...I'm the Cheating Partner?...

So I've been in this open relationship with my wife Jane for years now. We've always agreed on honesty and communication being key, but there's something about finding out she recently took a lover that has me questioning everything. It's not like it's new ground, we've both done our fair share of fooling around over the years... but somehow this time feels different. I guess because I was too busy being faithful while she was off getting her kicks. The irony isn't lost on me at all. But here's where it gets tricky - do I really blame her? Am I still cheating if we're both okay with it? Or am I the asshole for feeling betrayed by something we explicitly consented to, even encouraged in a weird way? Should I be pushing back against this now... or is it time to let go of that marriage altogether and just accept we've grown apart? What do you guys think? Am I the asshole here, or am I finally seeing things clearly? Comments below...