AITA for leaving my husband after discovering he was cheating with my childhood best friend?

I (34F) have been married to my husband, Ryan (36M), for nine years. We met in college, connected instantly, and got married three years later. Our life seemed perfect: a cozy home, two kids—Lily (6) and Max (4)—and a stable, loving marriage. Ryan appeared devoted, attentive, and trustworthy.

My childhood best friend, Sarah (33F), has been a part of my life for more than 20 years. We shared everything—secrets, vacations, and milestones. I trusted her completely. She had also been a part of our family gatherings and was practically like a sister.

About a year ago, I began noticing subtle changes. Ryan started spending more “time at work” or taking “late business calls.” Sarah also began visiting our home more often. I initially thought nothing of it—it was normal for a family friend to help out—but soon, certain behaviors didn’t feel right.

One evening, I returned home unexpectedly from work. I found Ryan and Sarah in the living room, sitting uncomfortably close, whispering and laughing in a way that didn’t seem innocent. I froze, unsure how to process what I was seeing.

Over the next few days, I discreetly checked Ryan’s phone while he was out. I discovered months of intimate and flirtatious messages between him and Sarah. They had been arranging secret meetups, sending affectionate texts, and even planning weekend trips together—all behind my back. My heart sank. The betrayal was deep, shocking, and personal.

I confronted Ryan immediately. At first, he tried to deny it, saying it was harmless joking. But when I showed him the messages and proof of secret meetings, he admitted to having an affair with Sarah for the past six months. He said it started emotionally and “just happened,” but I couldn’t believe it.

I also confronted Sarah. She admitted she knew he was married but tried to justify herself, saying Ryan had feelings for her and it “just happened.” Her lack of genuine remorse made my anger and heartbreak worse.

The emotional impact was overwhelming. I couldn’t sleep, eat, or focus. Every family memory—vacations, birthdays, holidays—felt tainted. I realized I could no longer trust Ryan or maintain a marriage with him. I asked him to leave and filed for separation.

Friends and family were divided. Some told me I should try to forgive him for the sake of the children, while others said I did the right thing—betrayal this deep is unforgivable. Months later, I’m slowly rebuilding my life, focusing on my children and career, and learning to trust myself again.

So, AITA for leaving my husband after discovering he was cheating with my childhood best friend?