Dear Jo, your mum is shitty.
For all the ills of people, it's always the parents' fault. I do believe that. Even if they're adult children. What they got when they were young, they got it from their shitty parents or legal parental figure. If they got shitty parents, and they turn out fine, it's all down to the children's effort to be and do better even if they struggle with it. The Fourth Commandment? Honor thy father and mother? Fuck it. ONLY if they deserve it.