Hi, thanks very much for your question. My name's XXXXX XXXXX I'm going to assist you with it this afternoon.
The action that immediately springs to mind here would be defamation (in the form of slander). You would first have to show (i) that the statement referred to you (which appears clear from the facts in your question); (ii) that the words were defamatory and (iii) that they were made to a third party.The problem with proving slander in this case relates to element (ii). Whilst the statement sounds like inappropritate conduct by the social worker, it is questionable that the words used (i.e. referring to you as a "wife abuser") would be deemed "defamatory" under the law. Not least because an opinion is generally not deemed defamatory where it has some factual basis and relevance to the circumstances. More importantly, in order to be deemed defamatory, the law tends to require the statement to have a negative effect on your reputation or expose you to contempt or ridicule. I appreciate that this is probably not the advice you wanted but I need to be completely honest with you.
Further, claims for defamation can be very expensive. However, if you just wanted to send a solicitor's letter warning the head of Wiltshire Social Services of the laws of defamation and that his team needed to tread carefully, this would probably only cost you around £100 and may instigate a response (although there are, of course, no guarantees). For what it's worth I think that the social worker has behaved poorly with regard to what is a very sensitive issue.
Please don't hesitate to let me know if I can provide any further clarification or if you have any further questions. Also, if I've been helpful, I would also be very grateful if you could remember to rate my answer. Good luck with everything.