I can totally sympathise with you. I chucked my ex out in 2004 for being a cheating, alchie, druggie ar*eho*e.
However as a consequnce i got lumbered with �40K of debt, which i am still paying off now, and will be for another 3years.
Its been hard, i worked 7 days a week for 2 years doing 1 full time and 2 p/t jobs just to keep on top of things until i got a pay rise, and i do sometimes feel bitter that my life is being affected because of him - cant buy a place to live, cant afford to have kids as cant pay the repayments out of mat pay etc etc
However, i'm still pleased i got him out of my life when i did, as having him around was no godd for me, and i'm sure the money situation would have only got worse.
I cant help you on benefits etc, but please try to stay positive, and do what your gut instinct tells you to do. If someone is toxic in yor life, you need to get rid.
Good Luck..