Stuck in debt thanks to CSA

I am now in a relationship with my current partner and have our own child.

My current partner was made redundant after becoming pregnant (which is another story!). My ex wife grills my son after each visit and if she thinks I earn any extra money, asks the csa for a fresh assessment of my income.

I now have a sole income and just can’t make ends meet but have to find £239 a month where as we three live on barely £100 a month. I live in a 2 bed flat where as my ex has a £300,000 3 bed house, having a £15,000 extension bening built and in recent years had holidays in Kenya and Gambia. She also has 3 jobs but the CSA seem unwilling to investigate as she has only declared 2.

She conveniently is a book keeper so knows the system. It seems that I will be in financial hell until my son hits 16 even though she has told him he has to go to college (no doubt to extract more money from me!)