Help Needed EX set solicitor letter

[SickOfTheEx]

Hi all,
Can anyone help me please?
I have an ongoing CMS case which the ex doesn't want to pay. The CMS are now at arrears and enforcement court action is now in process.
My question is I have just received a solicitor letter asking if my 18 son is in full time education and what course he is doing. My ex has not bothered with his son and only sees him for 2 nights a year. The parental responsibility agreement that he took me to court for has expired on my sons 18th birthday.
Do I have to respond to this solicitor letter?
Whenhe could be asking his son this question himself as he is of age now.?
I know why he is doing this as he is trying to scare me into dropping the CMS court case by going direct.
This man earns over £2,000 a week!!!!! And does not want to pay for his son. He lives in a 13 acre estate with an estate manager. Anyone would think he is the owner of Home Farm in Emmerdale. Lol.
Please can someone help me as he has tried harassing me I the past. I have had police involvement.
I am.sick of feeling so isolated, anxious and upset. At times I feel suicidal.
Is there anyone else out there going through similar issues? Many thanks for any help or support xxx

The CMS has been made by you, so communications on that matter should be with/ responded to by you. Is your son still in full time non advanced education?

• The CMS claim

The solicitor letter that he has sent has nothing to do with the cms case whatsoever.
Yes my son is in full-time non advanced education. Which he already knows that.
He is using a solicitor to contact me to try to gain more information for my 18 year old son that he could be asking him I his own right as he is now an adult. It's very hard to explain the full situation on here and typing gets misconstrued.
The CMS are dealing with him and his solicitors separately for the Cms case against him.
The cms deal with everything on my behalf as it is them that are taking him to court. Not me.
Thanks for your help xx