Why do ypu think you're an awful person, if you haven't even talked to this former girlfriend in years . . . . . or have you? When, exactly, was that snapchat encounter you related?

Telling her she's the most important girl in your life sure isn't going to cut it. She needs to hear that she is the only girl in your life.

Bring home flowers and keep being real sorry. That's about all you can do.