CSA taking an extortionate amount

I came home in Feb this year to find my ex partner of 20 years had emptied our house completely taking our 4 children. A couple of years ago unknown to me I found out she had run up a £19 thousand debit in credit cards which I agreed to take a load in my name, as she could not get one to sort this out (stupid now, I know!!) I have now after the split found she has also taken another £17 thousand pounds from our mortgage. I am left with the debt and now the CSA are wanting £130 a week from me. I see 2 of my children, but the elder 2 will not come.

I had an agreement of £100 a week with her which I have been paying directly into her account. How am I suppose to live with paying the mortgage and debts I am left with together with this maintenance! Does anyone have any ideas or thoughts for me. I am going out of my mind!!