I taught 7th grade English for 5 years. I loved my students and teaching.... I hated politics of schools and other employees. I watched schools throw students away, search out mold-able idiots as employees, and try to hide anything that went wrong or might make them look bad. I watched a high school teacher who slept with a student with no repentance just move to another state and continue teaching with the school helping her relocate, instead of filing charges and helping the student and his family. I watched teachers lock their doors and not allow students into the room for their classes because the teachers decided they needed a break and didn't feel like teaching - yet the students all got in trouble for not being where they were supposed to be. I watched schools hire math teachers to teach English because it was cheaper. I watched district employees grope female teachers and fire them if anything was said or decide not to hire them permanently if they did not react right.. ...... I did not have the stomach or mental capacity to stay in schools. I work in the mental health field now, and I am much happier.
I am not saying leave. I am saying you have to find the point that is too much for you and then decide what is the right move for you after that.
If you feel sick to your stomach thinking about going to work, like I did, it is time for a change.

As a person who deals with this type of issue on a regular basis, I will say, use the phone to be an objective witness in the future.

You will have to make a decision every single moment to stay in the moment, and do what works best for you. Since the investigation slanted in your co-worker's benefit, you know that you have to make changes that work for you.
1. You are responsible for what you say, do, and how you react. You practice in front of mirror different ways to respond positively and use those tools to keep calm, balanced, and comfortable in difficult situations.
2. Just because someone says something does NOT make it your problem. Use responses that work for you, even if it's just a smile and walk away. (One coworker said she was able to picture walking away, even though she was standing still ... and the bully was displaying behavior that everyone observed, and because she kept quiet, they had to deal with it ... )
3. Find your strength and give it a name to help you stand strong.
You are not alone. Best wishes.

Thank you to each and every one of you for your responses! I love the picture/cell phone idea! Also, I looking for other jobs outside of education...I can't handle how things are. I am so lucky to have all your support & well wishes. Thank you... thank you.