Hello, I'd like to help you with your question.
It sounds like your mother in law possibly had a personality disorder. She does fit some of the criteria for Sadistic personality disorder or maybe narcissistic.
Personality disorders are typically ingrained behaviors that someone develops, usually in response to being raised in a dysfunctional home. The person could not get their needs met (for unconditional love and attention) so they developed other ways to get what they needed which usually involved dysfunctional behaviors. When they grew up, they continued these behaviors even when they were no longer needed. Your mother in law might have been treated so poorly at home (cruelty, torture often causes a person to develop this type of behavior) that she developed a lack of sympathy for others in pain. She may also have learned to enjoy inflicting pain on others.
Another personality disorder that might also describe her behavior is narcissistic. People who are narcissistic also enjoy hurting others.
Here is a guide to personality disorders to help you find which disorder fits her:
And here is a link for sadistic personality disorder:
the right thing in keeping your child away from your mother in law. What she did could have caused your child so much distress that he could have been traumatized. Since you acted to protect him, the chances he was harmed in any way are minimal.
I hope this has helped you,
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