Imo nothing justifies violating HIPAA (are you in the US? If not then obviously HIPAA doesn't apply)
Boundaries exist for a reason. In your position I would feel that the boundaries of the relationship had been massively violated. My therapist is a professional and there are rules that are supposed to be in place to keep professional separate from personal. He has my emergency contact info, he can call the cops, but he does not have the right to intrude into parts of my personal life that weren't part of the "agreement," including contacting anyone else from my personal life.
There is usually paperwork at the beginning of therapy where you give them permission to do certain things like contact certain people under certain circumstances. What's the point of that paperwork if they're not going to act within those constraints?

I'm glad your therapist cares, but my personal opinion would be that caring isn't an acceptable excuse for ethical violations, and I see this as an ethical violation. Therapists have to accept that they're not allowed to do anything and everything they might want to do. That's why rules exist. They don't get to make these decisions for you.