Please help me see! Why did he do this he got his divorce?

I married a N and did not know what the problem was until he was gone and I found this site. He left me a few times during our short marriage(1 yr.). When we got married he told everyone how proud he was that I was his wife then all of a sudden He was so mean when he left the last time. he got fired from his job right before our wedding. He left me for a woman that he was once engaged to a few years ago and his family said he left her about 3 times also. He spoiled my name by telling friends and his family members that I am a lunatic and I need help. He tells everyone that I need serious medical attention because I'm crazy. I was so humiliated by this I didn't go anywhere and I said nothing and kept to myself, I didn't even show up for court because I knew he would do or say something there to hurt my feelings. My Lawyer handled all of my court appearances and I never contacted him since the day he left. He has NOT seen or heard from me and we have been split for 8 months. It took only 2 months for our divorce to be final. on the day of our divorce, I did not go to court but when he got out he sent me an email that was very long and hurtful. calling me names, talking about my looks basically calling me ugly. I did not respond so then he text my daughters phone and threatened to get me fired.I didn't respond to that either. My child (9 yrs old not his child) was so afraid for months because she got the text. He got his divorce so why did he do this? Why call me a lunatic? Why send the email and why text my daughters phone? He is still with the ow is he nice to her? Please answer all questions I am struggling with this. Please tell me why they do this?