You know amaze, I was empathizing with your situation and wishing I had more advice. Then I wondered. How much impact do you think g-dad is having on all of this? If your boys see gpa modeling verbally abusive, degrading behavior towards you - then they are bound to follow suit. I know money is horribly tight, and that you have made some amazing steps with Al-Anon, etc. - but have you thought about trying to move out some more?
On an interesting similar note - my difficult child used to be the worst at tearing me apart verbally. Then H. died. I am not sure if it was him seeing me rocked to my core in grief, or the fact that I too could die - but there was an entire paradigm shift in his treatment towards me. I cannot explain it in any other way other than I think, for once, he saw me differently. He saw me as whole, vulnerable, but not as his Mom.
Just wonder if getting a paradigm shift for your boys, where they see you as a person struggling to get the soup on the table every day - and sorry thats all we have - would be a reality catalyst for them. Just a thought.