I'm so sorry. Remind yourself that other's feelings aren't always the truth... it may be true HOW they are feeling, but feelings are so fickle that they might be incorrect. Validate her feelings, and then analyze to see if maybe there's some truth to it... then change what you feel called to change and just hug and forgive your friend for any "false" feelings.
Sad and sick to my stomach. A longtime friend shares that I have not "been there for her" enough. I'm sorry I'm not perfect.