Advise please?

How do I react?I’m so angry currently. My daughters ex girlfriend is talking nonsense about my daughter on Twitter. They have been broken up nearly 3 years and her ex continues to talk badly of my daughter.There were problems in their relationship, both were needy, demanding and toxic for one and other.My daughter had mental health problem and when they split up my daughter spent a long time in therapy talking about past trauma and then reached out to her ex apologising for the time she had been bad to her.Please be aware that my daughters ex also had issues, she never wanted to be away from my daughter and she never wanted to go home. Many a time I heard the ex having a good at my daughter and them both ending up in tears.My daughter has made such progress during and since her therapy and now she is back at university studying her masters.My daughter has asked me not to contact the ex but I’m so angry at her ex’s portrayal of my daughter.Please no hate, I’m new heard and I’d appreciate honest replies.Thank you in advance 💕 via /r/Parenting https://ift.tt/32A2Roz