Responses
I would put two tags: rape and abuse.
She surely was raping him, but also was abusing in a violent and verbal level. Which maybe drew him to isolate from people. His stutter at such age could be a consequence of her abuse.
Why is "abuse" and not "rape" the tag people picked? I was really surprised, not in a good way. My own suspicion is that it's the genders involved. The ages and the status of the people involved make consent impossible. It's rape. Abuse doesn't cover it., not as a reader warning label, anyway.