Assalamu alaikum - I was harmed by an older teacher and he's getting engaged; should I tell his fiancée?

Assalamu alaikum. I'm 15 and I need advice. I started private online tutoring with a well-known science teacher. He became closer to me, messaged me a lot, and over time he groomed me and made things sexual. He took advantage of me for about five months. A few weeks ago he suddenly stopped talking to me because he said he was going to get engaged. He not only sent sexual messages and assaulted me, he also sent money to try to show he “loved” me and to “spoil” me. When I got upset and pushed back, that’s when he left. Now I’ve learned he’s getting engaged to someone who is very dear to me - someone with a pure heart who I care about. He used to be a person who supported me when I was at my lowest, and it hurts that he could do this. I’ve realized more clearly that he groomed me. I feel ashamed that I replied to his messages, and I’ve sincerely repented to Allah. Still I feel angry and I want the woman he’s getting engaged to know what he did. If she knew, I believe she wouldn’t want to marry him and might report him. I don’t have the courage to tell my family - I’m afraid it would cause big problems at home and in my life. I also have no one else I can talk to and my mental health is really suffering. So I need your opinion: should I tell her everything to try to stop this engagement? He is a predator and recently assaulted me. Would Allah want me to speak up? I don’t want someone with a pure heart to marry someone like him, and I can’t keep this hidden any longer. Please advise me on what the right thing to do is.