Stalking and harassing ex who sends friends and family msgs slandering

Hello, There is a person who I broke up with after 2 weeks of dating due to hiim being highly unstable and emotionally abusive. He was later hospitalized and treated for some psychiatric illness. But he kept disturbing me constantly in reality and online, even threatening to spread news that I had been sexually assaulted. I finally complained to concerned people in college and he was, I think, suspended. This was 3.5 years ago. But over the last year especially, he has been constantly sending me emails from different accounts asking me to talk, explain why i left him, and that because he helped me in some cases, I should not have left him, and even sent messages to my family slandering my reputation. He does this despite being married now. I put all msgs in spam, but he keeps sending from new emails, and to my friends, even labeling my male friend as a sexual offender. Can I take legal action to stop this as it is extremely stressful for me?