I can't shake this feeling

It's been almost a year, and I still feel sick about it. I lied to my best friend, Amy, about something really stupid. We were both up for the same promotion at work, and she asked me point-blank if I'd heard anything. I knew I was getting it, but I told her I hadn't. Just completely lied to her face.

I got the promotion, obviously. And she was... fine about it. Said she was happy for me. But things haven't been the same since. I see her differently, and I know she sees me differently too. It's like there's this little wall between us now. I hate it. I should just tell her, right? But I'm so afraid of making it worse.