It's Complicated...

I'm engaged to Sarah, who I adore more than anyone. But tonight, as I was coming home from work, a girl named Emily called me out of the blue. We hadn't talked in years, but there was something electric about reconnecting with her again after all this time. She's always been so magnetic and unpredictable. We ended up meeting at an old haunt of ours and... things got heated. I don't know if it's just a one-off, or if it means more than that. I've never been unfaithful before; I'm not sure how to think about this, but it feels like something has shifted. It’s hard, because Sarah trusts me completely, she doesn’t even check my phone, and I’m supposed to be the responsible one here. I keep thinking maybe if I just don't tell her, it won't matter... But the guilt is eating away at me. What am I going to do? Part of me wants to be honest with Sarah right now and see what she says, but another part of me feels like this was something that happened in a moment of weakness, I shouldn’t make a bigger deal out of it than it needs to be.