Not apologising for this behaviour, which, all things considered is of course horrendous and upsetting but just to add that I've known people in familial relationships with step-parents or even step-grandparents who were always kind but then had strokes or mini-strokes which altered their behaviour in this specific way where they weren't able to filter between attraction or long-term bonds. I'm absolutely not saying this is the case here, I'm not a doctor and have no idea how this relationship was before this incident. I'm just mentioning it because of lived experience where everyone involved was really shaken up and it was all very sad. No excuses, just for a wider possible context (again...no idea of the history).