Im a horrible kid

The only way to free yourself from this is to tell everyone that you lied about her. You feel miserable about it now and wish you could take it all back.
If they ask, tell them why you did it. For instance, perhaps you were angry with her over something particular and wanted revenge.

After you've told them, then tell her,
say you're sorry,
and you've confessed and corrected it with those you told,
and you've learned your lessons about lying and revenge.

Accepting responsibility and the consequences for one's actions is a major part of growing up.

You have a good conscience, so let it be your guide.

You should be honest & confess what happened

Sometimes it's good to confess and get things off your chest , personally I don't think this is one of them she will probably be hurt even deeper I would keep it to myself and make it up to her at every opportunity and learn from your mistake

That's why I don't like to talk about my marriage online. I don't mind telling people that I cheated because it was a long time ago, it's over and I've moved on and I like to disclose it in case they find out later.

You need to be honest about what you did. You're grown enough to know better, no excuses, be accountable for your actions

so go to her and cry and tell her you are sorry and that you love her, and post publically you lied and then just go silent a while

why did you tell lies about your mom