"Unless my financial future is secure i can not have peace of mind. The only way to do that though is to file, and i am terrified to go down that road. I know how it destroyed my mother when i was young, so it brings up wounds from the past."
Then do something about it. Essentially you're saying you're (for lack of a better term) f*cked whatever you do. Well that may be so, but it will be temporary. In the long run things will get better for you.
But they will only be better unless you start making a decision about your life.
It seems you are fine to blame your H for your sitch, but you haven't done anything to make your life stable long term.
Here's the reality... Your H's gone. You are worried about your financial future so the only way you are going to feel secure is to get a D.
Then get a D.
Stop thinking about it, just do it. Will it make your life easier? Who knows? But you've got to take a step on your own in your own life. You are the adult here but you are letting your son...YOUR SON...see his mom disintegrate before his very eyes. He's going over to your MIL's place because there's stability there. Unless you get off your @$$ and start giving him the stability he needs, you will lose him as well. Is that what you want?
Is money more important than your son?
M-43 W-40 2D - 9 and 5
Emotion, yet peace. Ignorance, yet knowledge. Passion, yet serenity. Chaos, yet harmony. Death, yet a new life.