my best friend hates me now

so my best friend of 10 years and i had a big fight last week. it was about some small stuff but it kinda went to us talking abt all the times i messed up as her friend. we did this long time ago too, when i told her i couldnt keep her secret abt boy she liked in high school. now she says she cant trust me anymore and hates me because of that old thing. i feel so bad cus shes the first person who understood me when i was going through hard times. what should i do? am i really a bad friend? or can i make things right again somehow?