I feel suicidal over "incest"

This might come off as bizarre to people but it is actually real.

My aunt got a bf. He had a son from a previous marriage and we have no blood relations. I had a crush on him and dated him in high school at like 17 years old. Everyone knew.

Now my aunt and her bf got married. He is technically my step cousin. This is seriously affecting my mental health. Idk if its incest cuz we dont have blood relations (thats why I wrote incest in quotes) but makes me want to self harm because I feel like I did smth horrible.