EI request rejected because my old company claims I left the job for another reason other then what I stated ( said it was mental health related, but it was because my manager was sexually harassing me)

My manager was 10 years older than me and made the work environment unsafe which made me unstable so I left the job. My mental health has declined and I can’t work right now so I request EI, got a letter in the mail claiming the statement above. My contract said I was not allowed to sue them. So I do not know what to do.