Why did orson's mother lock his ex-wife in the attic???

I am pretty sure it was to stop her from going to the police. Maybe she is waiting for her to get control of herself. If she went to the police everything would be over. She hates Brie but I think she loves her son on some level. She wants to see him suffer though so I don't see her as being the loving mom.

I think that Gloria didn't want Alma to tell the police the orson killed Monique, after all Gloria would get in trouble for covering up for him.