Oh Blue Oh Blue
My heart just broke reading all this. You are getting hit from every side on every level. Reach out for every bit of help you can find... I am pretty certain you would qualify for more help than you could imagine. You oldest boy .. I mean WOW ... He is changing, changing for the good. You are a wonderful Mother. I know it is hard to think of the positives in your life, they are there just hard to see right now.
Hang in there and know that things happen for a reason, You have something wonderful that will come into your life.