My mother enable her husband's physical and sexual abuse towards me and won't stop trying to contact me. What can I do so that it stops?

EDIT: mistake in the title, she ENABLED, I'm sorry Frenchie here.

I didn't press charges, it's been five years since I've cut contact.

As time passed I deleted all social media in order for her to not contact me but deleting my email would be harder. She tries to contact me probably one a year and if fucks me up big time. This summer she sent me an email asking for us to explained ourselves, I answered two months later (because it was too hard psychologicaly) with a list of events and the request that she never contact me again. She contacted me again today saying that she has a right for an explanation and that she never wanted to hurt me.

I don't believe I have the basis to press charges as I would probably need a confession since it was so long ago and I have no proof, but I know that they could be forbidden to contact me if I do but only for the lenght of ghe legal process and condemnation if there is.

I don't there is ground for harassment since her attempts to contact me are not that frequent, would pressing charges for physical and sexual assaults be the only way so that she leaves me alone? Should I just threaten to press charges in the hope that she leaves me alone?

The impact of what happened affects me every day, the nightmares never stopped, I'm dealing with suicidal ideation since I'm a teen and I can't hold a job. I just can't have her writing to me like that, it's destroying the very little mental stability I have every time.