How to file charges against an abusive boss?

I am seriously thinking of filing charges against my abusive boss, but I don't know how to start or if I should. Please advise.

We had a huge emergency at home, which required my immediate attention and needed me to leave work for the day. I was working overtime on that day which was actually my day-off.

At the time, I was assigned on location, so that meant I just couldn't leave my station just like that or just abandon my post. A family member who lives alone had a heart attack. I asked my boss if I could go to attend to the crisis. He said no and yelled and said "Work is work and I don't care if she is dying."

I asked the higher ups to allow me to leave my post and had made arrangements with colleagues, who were more than willing to take my place so I could go. The higher up sent me back to my boss who again didn't allow me to go. He has been verbally abusive amongst others not only to me but to others prior to the emergency. But that's another story.

Because I wasn't able to attend to the emergency and get everything sorted out, I was forced to resign instead and resulted to a death of a loved one.

I'd just like to know if I could file a case against my former boss? I am not after money. I have heard that he is still abusive to my colleagues who are afraid of speaking up and losing their jobs. I badly want to teach him a lesson as well.

I forgot to mention, his immediate superior is allegedly romantically involved with him for over a year now, so I heard. His boss also covers for him every time he does something wrong.

The Human Resource Department head somehow cannot seem to put these two in their right places.

What would you do if you were me? What do you suggest?

Thank you for your time.