Hi Brookester,
im sorry you were so betrayed by a person you trusted. that was a big betrayal and stepped way over the line imo. where i live the most therapists of any sort will do is leave a message with their name/number as appropriate and request that i call them back. ive never had anyone leave more than that on my voicemail even though it is my cell phone which only i access.
on the other hand there may be a valid reason for what she did (not that i can think of one!) so i would take it up with her personally to find out if there was a reason she made such a terrible mistake before you get a lawyer involved. maybe you can work it out between you so that she understands what a big impact it had and how damaging it could have been to your relationship or maybe it is too big a betrayal and you cant build back up a relationship of trust with her after it but at least hear her out first.
i wish you luck with this and again am sorry this happened.
take care
biiv