I Lied About My Job Experience

So I started this new job at the mall a month ago. It’s okay, but nothing really special. Just another place to punch in and out of, you know? The thing is, on my application, I kinda exaggerated about how long I’ve worked in retail before. See, I told them I had five years under my belt, when it was more like two. I wanted the job so badly because they were offering training for an online certification that would look good on my résumé. But every time I go back to the office and see all these other kids there who have actual retail experience, or even a degree in something related, I feel bad about lying. It’s not like anyone knows yet though. One day we had this customer come in who was just rude from start to finish, but still trying so hard to seem polite. Like she’d ask me where the women’s socks were and then sigh and roll her eyes before I could answer. Anyway, after that, my manager wanted to talk to me about my sales numbers and how they haven’t been doing well. And you know what? She mentioned something about a background in retail being so helpful for things like cross-selling and upselling, but I couldn’t tell if she already knew the truth or was just suggesting it. So here’s the thing: if I get let go because of this lie and how it affected my work, I mean, even if it wasn't the main reason, then that would suck so much. But what do you think? Am I really the asshole here for fibbing a bit on an application?