This article, directly from APA's website, describes when a therapist needs to break confidentiality.

• "...in order to protect the patient or public from serious harm" which typically covers suicidal intent (with an expressed plan) or an expressed threat to harm others,
• "...ongoing domestic violence, abuse or neglect of children, the elderly or people with disabilities,"
• "...if they receive a court order"

I'm not a professional and obviously I don't know when a therapist would need to disclose if it happens to deviate from the norm, but I hope this helps in addressing what is usually necessary for a confidentiality breach.