Engaged and Experimenting with My Best Friend's Wife

So I'm this forty-something professor engaged to my best friend, Alex. We've been together for like three years now, since the start of my divorce from my high-maintenance ex who was always giving me a hard time about teaching and not making enough money at the university. Anyways, long story short, I bump into one of my old students, Maggie, who's married to Alex's brother. We get along super well. She's been through her own divorce and she gets what it's like to be a single mom with a kid after a failed marriage, which made us feel close even though we're decades apart in age. I end up giving her some advice about teaching kids at home or getting them involved in local activities, since that’s kind of my thing. Then one day she reaches out asking for more help. We chat and I can tell there's this mutual attraction building. It's like a slow burn and it feels so wrong but also just so... natural? Anyway, long story short, we end up hooking up in my classroom after hours with Alex still married to his wife, who’s Maggie's sister-in-law now. We’re all adults here, nobody gets hurt, everything is consensual. I mean yeah it feels a bit taboo but honestly we were just playing around and seeing if the chemistry worked out. I don't regret it but also feel weird about telling this story since I know how complicated everyone’s lives are. But hey, sometimes people hook up with friends’ spouses or siblings, right? Just wish it hadn’t happened while Alex was still married and we weren’t fully on our way to a committed relationship together yet. Anyway, just wanted to share, not saying it's the best thing ever but it sure did get me thinking about how complicated relationships can be sometimes.