How awful for you and your siblings and frankly everyone!
I'm replying as I can see no one has, even though I don't have sufficient experience to really comment. I'd like to think that the Doctor would have informed social services if there are any children involved and from what you describe am amazed that your mum still manages to hold down a job at all. I'm also surprised that the doctor could not or did not recommend any medication.
My suggestion would be to create a new post on https://www.mentalhealthforum.net/forum/
which has far more active users than this forum which is typically quite quiet. Hopefully there you might receive some better advice.