This might sound silly, but what helps a lot of people is public transportation. I know being on buses/trains/what have you can make a lot of people even more anxious, but if you're looking to really separate your work life from your home life, this might be a good place to start. Taking the bus gives you at least a little time to "simmer down" and really think about your feelings and the reasons behind them. I can get anxious at school just like anyone, and I have to deal with a lot of people I don't like, but I've found that taking the bus (it takes me an hour to get home) distracts me and helps me come to terms with my feelings. If public transportation makes you uneasy, then perhaps you could make it a habit to go on a long walk or a bike ride after work to give yourself a minute to "purge" your mind.

Secondly, what has helped me in the past is yoga and meditation. I went to these classes a couple years back and we did breathing and stretching exercises. We were repeatedly told to empty our minds of all everyday stresses and to just feel our presence in the moment. When you have an outsider telling an entire class of people to stop thinking about work, you quickly realize that you're not alone with crappy feelings and that everyone deals with unpleasant things every day.

Also, please find comfort in knowing that there are plenty of other jobs out there and that this doesn't have to be permanent. I've had some terrible bosses, similar to yours, and I've also had some very kind and understanding ones. Perfection isn't the goal here and there are down sides to all jobs, but if someone at work makes you miserable, it may not be worth it.