Why would the CSA do this?

I have 3 daughters from a forced arranged marriage to my first cousin from Pakistan.  I had a breakdown 3 years ago and finally came out to myself and tried to do an amicable separation from my wife.  I lost my job due to my ill health and she found out I was gay and outed me to everyone.  My family disowned me and I was too ill to work on mental health grounds and received disability living allowance.  

I offered £200 per month however she contacted the CSA and because I was on benefits she received £5 a week.  She poisoned the children and got social services involved by making every accusation possible around abuse to the children and violence that was possible whilst I was in hospital on a mental health ward.  Social Services were horrible and despite finding no evidence and the allegation of sexual abuse against my own daughter being denied later on Social Services and they have made my life hell.

My daughters do not wish to see me, my ex wants the house off me which I have said she can have.  She has taken the car from me which I have given back and throughout this I have done my best to be amicable and not be rude or call her as some do because no matter she is the mother of my children and for that I have to respect her.

Earlier this year I got offered some consultancy work through a company with my ex employer which I took and came off benefits.  The CSA wrote to me and I gave them the companies name and told them to contact the company as well as providing my pay details.  My ex stalked me on the internet and reported me to the CSA for working for the ex employer.  The CSA have written to both the company I work for and the company that has outsourced this work to the company.  Why would the CSA do this and what powers do they have to ask