Mental harassment and defamation by ex wife

We got divorced last month after 7 years of marriage. This month my marriage got fixed with another girl. I knew this girl from before even when I was married. Now my ex wife is getting really mad and angry. She called me at 4 in the morning and kept speaking nonsense for more than an hour, unfortunately I did not record that call. Then she started texting everyone in my family and friends saying that they should know that this girl is the reason for our divorce and she is surprised to see things moving so sudden and then she texted me that pretence of yours and your family to silently get the divorce so that you can jump on to another relationship is clearly in front of me now. And then when I told her that I don't have to justify anything to you and I don't want to talk to her anymore she said, oh look who is showing attitude, a cheater flaunting his wingsAll this is affecting my new relationship and my fiancée is thinking of breaking it. Please suggest what I can and should do.