Why Did I Tell This Lie?

I've been separated for a few months now, and lately, I keep overthinking this one thing I did before we split up. One day, my ex caught me looking at porn on her laptop, something she really hates, and I panicked. Instead of owning up to it, I spun this ridiculous story about being sick and watching documentaries all day...like that’s even believable. It was just a momentary lapse in judgment, but now every time I see her, I feel like such an idiot for lying about something so silly. Maybe she figured out the truth; maybe not, either way, it's eating away at me.