My Girlfriend (26F) Cheated On Me (30M) and Struggling with what to do

I (30M) have been with my girlfriend (26F) for over three years. A few weeks ago, she cheated on me while extremely drunk, and I’m torn on what to do.

The past nine months have been incredibly difficult. I suffered a major leg injury, lost my job, and fell into depression. Without health insurance for physical therapy, I couldn’t exercise—my main coping mechanism. As a result, I withdrew emotionally, neglected our relationship, and stopped being intimate. I now see how much distance had grown between us, but at the time, I was too caught up in my own struggles to recognize it.

A few weeks ago, we went out with friends. I left early for another event, and she stayed behind. In the short time we were apart, she ran into an old college friend, got blackout drunk, and ended up sleeping with him. She broke down immediately afterward, came home in distress, and confessed the next morning.

She is deeply remorseful and disgusted with herself. Friends and family are all shocked because this seems so out of character for her—before this, she had been an incredibly thoughtful, caring, and loyal partner. She insists I’m the love of her life and wants to work through things, acknowledging that real changes need to be made.

The biggest red flag in our relationship has always been her drinking. She rarely drinks, but when she does, she completely loses control and becomes someone unrecognizable. This was already a point of tension, and now it’s at the center of this betrayal.

Looking back, I realize our biggest issue was a lack of communication. I had completely shut down due to my depression, and if I had made even the slightest effort to bridge the gap, I don’t think we would have reached this point.

I know cheating is inexcusable, and I’ve ended relationships over it before. But this situation feels different. She has been the most supportive, caring partner I’ve ever had—until this one terrible night. I don’t know if this is something we can rebuild from, or if I’m just trying to justify staying.

For those who have been in similar situations, how did you decide whether to stay or walk away? What helped you work through it, or what made you realize it was time to move on?