having dealt with many people who have had mental illnesses. I say it's simple because it's simple to say... to internalize takes practice.
You only have to remember two things:
1. Yesterday is unimportant. Stay focused on today and tomorrow.
2. People do not make you angry. You allow yourself to become angry by what people do.
If you will do me a favor, commit these two sayings to memory and use them whenever you feel like shit.
To be completely honest, I have been following your posts for a few weeks and wanted to say something. I understand exactly how you feel about life and tend to agree - when I allow myself. What I have come to realize is that I cannot affect the "world", only my little slice of it and I try to act in a manner consistent with my beliefs. I am honest with everyone, I do not try make others look bad, I give to the less fortunate, I hug my son at least 10 times a day, etc... The other thing that I have come to realize is that life is very short, only so many years, months, weeks, days, minutes, seconds. It is a waste of precious time getting upset about things that I cannot control.
Change the tape. Do something constructive to help your ex-peers in the lawfirm if it will help your sense of justice. Do it in your spare time though, and don't let it consume the precious minutes you have remaining. Idle hands lead to idle minds, so keep yourself busy before starting your next career.
FWIW, I (like most everyone else on the planet) and my sanity are on a razor's edge. Deep down I constantly keep watch on the house of cards we call our economy, our safety, my children's future. But day to day I keep my eye on the road directly in front of me, you never know what could jump out in front of you.