Thank you. There is actually no right to privacy in these situations - a private chat on a messenger program is not in any way protected by privacy laws. That is only the case in relation to the 'host' and by that I mean the developer that runs the app. So for example, WhatsApp would not be able to share your messages with a third party as they will have strict data protection obligations. However, none of that applies to the people taking part in the chat, and they will be entirely free to share its contents. Therefore, someone taking a screenshot of a chat and passing on to someone else will not be acting illegally in any way as they would not have had any formal legal privacy obligations to start with.
In terms of whether a claim can be made against you for things said in a private chat, that is entirely possible, at least from a legal perspective. However, in reality it will probably not happen.
The most likely allegation here would be for defamation and whilst this may appear to be a potential case, such claims are rather difficult to pursue. Many people are keen on suing for defamation without having full appreciation of the law or practicalities in doing so. I will try and clarify the position below.
First of all, certain conditions must be met for the statement to be classified as defamatory. These are:
1. There has to be a defamatory statement - the assessment that is often used to establish this is whether the statement tends to lower the claimant in the estimation of right-thinking members of society generally
2. Its publication has caused or is likely to cause serious harm to the reputation of the claimant – this will vary based on what effect it will have but it really has to be something sufficiently serious
3. The statement has been published by the defendant to a third party (a group chat can be sufficient)
4. The claimant must prove that the words complained of were published about him - this should not be an issue if the claimant is named or clearly identified.
Whilst it may be easy to prove that defamation has taken place, the legal process of pursuing such a claim is often complex and prohibitively expensive. A claim must be made in the High Court and will likely require the help of professional defamation lawyers, so the costs will often be high right from the outset, usually in the thousands. There is also no legal aid available for such claims so the complainant must fund these personally.
You must also consider whether you, as the publisher of the statement, can potentially defend the claim. For example this can happen by proving the statement was true or an honest opinion which could have been made based on the available facts.
So a threat to sue you for this can be real, but practically and realistically it is probably unlikely to happen and will most likely just remain as a threat.
I trust this has answered your query. Please take a second to leave a positive rating by selecting 3, 4 or 5 stars above - this is an important part of our process and recognises the time I have spent assisting you. If you still need me to clarify anything else, please reply on here and I will assist as best as I can. Thank you