She only confessed to you because she realized she was caught. She did not do it because it's about trust or because she wants you to trust her more, or she would've brought it up initially or when first confronted.

You specifically mentioned she originally doubled down. Then, when you revealed evidence/proof, she was lying suddenly she was lying to avoid having that conversation with you.

As the other person said. If you hadn't confronted her about this she would've been fine and happy lying to your face about this.

I'm not saying she would've cheated on you or not. But she wants you to trust her when she blatantly lied to your face multiple times. She's playing you.

It's like someone stabbing you in the back. You turn around and they have a knife in their back and they tell you to turn around. They promise they won't stab you again. It doesn't make sense.

Btw the more I read it your did handle it very immaturely, but it still doesn't change that she's playing you.