Anyone else hate people like this?

Ok so I have had the displeasure of running into a few people lately, including the mother of my child, who have no accountability for their actions. I have seen how much of a backstabbing liar that people like this can be. My sibling is also having problems with individuals like this. Is it just me or does anyone else just have no compion what so ever for people who have no values, no decency, and no accountability for their actions? People who don't even really acknowledge it when they wrong you, is who I am talking about. It's like these individuals are completely unrepentant. I never knew that my ex wife was this way until she got pregnant then she took off her mask and showed the real person behind the facade. How do you deal with individuals like this in a legal, civilized fashion? Now my child is showing signs of being like his mom. This is a night mare. Any tactics for spotting these individuals? What signs do you look for, and how do you get these people out of you life once they are in?