Am I the Asshole in My Private Life?

I recently got divorced from my wife of 25 years. It was mutual and mostly due to irreconcilable differences, but there were underlying issues that I now see played a part. During our marriage, while we both had separate interests and hobbies, her primary focus became the kids and her health, leading her to become increasingly introverted and less engaged in sexual activity. As for me, after years of being a professor at the same university, I began attending workshops on campus that catered to older professionals looking to explore their sexuality beyond conventional norms. At these workshops, I learned about something called 'ethical non-monogamy' and found myself intrigued by the idea of casual encounters without strings attached. One day, while we were still married but my wife had become distant both emotionally and sexually, I decided to try this out for myself. I started meeting someone from one of the workshop discussions anonymously through an app designed specifically for discreet arrangements between consenting adults. We met a few times over several months, keeping it all very secretive and always using protection as agreed upon beforehand. The encounters were brief but intense; they served as a kind of release that helped me deal with my own frustrations at home. Eventually, I found out about an upcoming workshop where we could meet in person without needing to use the app again. The night before our planned meetup, however, my wife unexpectedly returned early from her mother's house, where she had been staying since separating. She was there much earlier than expected and caught me by surprise, not quite prepared for what I might encounter should we cross paths. After a tense evening of awkward silences and unresolved tensions, the workshop happened as scheduled with my new partner. Now I'm left questioning whether pursuing these arrangements outside our marriage was ethical or necessary even though everything I did was consensual among involved parties. Is there such a thing as an 'okay' extramarital affair if it's between adults who are fully aware and have agreed to the terms? Was keeping my wife in the dark about any of this ever justified, considering we were effectively living separate lives anyway? Am I justifying my behavior too much here, or could there be valid reasons for why what I did might not make me an asshole?