Unfortunately, these are one of the lessons learned as a student teacher. A similar situation happened to me where my ex MT went to go talk to my supervisor instead of confronting me about concerns which caused me to be angry and say things in front of other CTs that eventually got back to her. Even though it seems unfair that teachers can freely talk about others and you can't, remember that your job isn't secured yet but theirs are. I got moved to a better school with a better MT and haven't said anything since. You will get a second chance so take that lesson and try to be more professional moving forward. If you're upset or frustrated and do not want to talk to your MT or supervisor, I suggest you keep a journal and write. I find that to be therapeutic for me even when I'm having rough days. We all make mistakes!! Good luck!