How should I react to a friend that didn't keep my secret after she promised to

Keep her as a friend but realize she can't be completely trusted. Give some time and opportunity to let her reveal herself. Like at some point maybe mention how you can't believe so-and-so knows about such and such, but I'd be reluctant to accuse her directly. You will learn about your friend by not painting her into a corner. In the mean time look for better friends.

A friend like that ain't worth keeping. Good friendships are founded on mutual respect, and she clearly didn't respect you enough to keep her promise to you.

I'd tell her how hurt and betrayed you feel. Maybe it's a one-time thing and she knows she messed up, but it'll be hard to trust someone like that ever again

I'd definitely raise this with her and ask her why she betrayed your trust and why you should ever trust her with anything...

[But I think I'd not trust her for a while, if ever.]

Take it easy and let life go on.

When you yourself can't keep a secret, how do you expect a friend to keep it ?

So remember that it's not good to keep secrets.

I'd first rule out misunderstandings. Do you know what she revealed was secret? Did she understand that what she revealed was part of the secret? How deliberate was the revelation? Did she deliberately go to someone and say exactly what you said? Did she just accidentally blab? Did someone just read her body language and figure it out? Might she have felt some kind of pressure to break her promise once she knew what the secret was?

Never tell them a secret again and slowly distance myself from them.
Eventually friends becomes somebody that you used to know.

Forgive

Talk to her about it

Try to forgive

depends on what she told. was it something bad, or a secret,

remain friendly but NEVER tell her another thing in confidence

Mixed replies:)

Tell a secret of hers

She's obviously not a good friend

Never tell her anything else again that you don’t want out there

The only way to keep a secret is not to tell anyone