Advice for the future: When you're writing an email while angry, save it in draft form. Go ahead and write it as angry as you want in the first draft, just don't send! Read later, at least a couple of hours, next day if possible. More often than not, you'll have calmed down and be able to take the edge off and send a professional correspondence. Obviously too late for that in this situation but it can help you in the future.

I won't offer any advice on mental health, as I'm not equipped to do so. I will say I've had similar disputes with co-workers in a few different offices. Of course, we always feel like we're being wronged and our co-workers are the problem, but after having issues like this in several different settings I had to acknowledge that I was at least PART of the problem. It's something I've only learned over time, but now over halfway through my career, I've learned how to handle conflict properly and not let it get personal. Try and see things from others perspectives and realize that not all conflicts can be solved. Learn which conflicts are worth engaging in and which ones are better off ignoring.

Good luck!