Most Helpful Girl
Sounds like you just missed the chasing, and if you really ask yourself if she's the one for you you might find she is not. Best to let them both go, chalk it up to a lesson learned and find someone else. New best friends will be had and new girlfriends will be had too. Just because she was your childhood best friend doesn't mean you need to keep her around until you're both 80. Things happened, time to move on and learn from the mistakes. She's obviously doing what's best for her by moving on and not wanting to speak to you - so if you truly valued how she felt and if you loved her, you'd let her go in peace and not interfere with how she needs to heal from what's happened.
Most Helpful Guy
So, let me get this straight... You finally achieved the DREAM so many guys have of actually getting with the girl they've been pining over big time who sadly happens to be their friend. You had it! You did what few men in the WORLD can attest to doing, and you... What? Went out and felt like getting some strange.
Well, I have a message for you, good sir, from every guy who has ever loved a female friend and every girl who has ever been cheated on by pricks like you: GO FUCK YOURSELF :)