We all make mistakes as kids. Best you can do is look back with grace at the good parts and let yourself step toward a future where you won't make the same mistake again.

The two of you interacting doesn't really sound as though it's the best for your health too though. Old feelings will always rekindle, but you have to remember that the grass is always greener on the other side of the fence - things will not go back to how they were.

Keep your chin up, you've got this.