To expect children not to read my messages?

[ChampagneTastes]

I am in a group chat with a number of mums at school. we discuss all sorts of things, make jokes, share concerns, discuss our children. So far so normal, right?

Turns out that at least a couple of the mums regularly give their phones to their children who on more than one occasion have read some of these messages.

I am a sweary person. I don't think I've said anything that I'm ashamed of but I've certainly said things not intended for a young audience. It has been suggested that I should tone down my language but my feeling is that it is not me who is the problem. I very rarely give my children my phone but if I do I am watching them and, quite frankly, they know to only use the particular app they have asked to use.

Am I being one of those smug mothers who think their child is better than everyone else's? (Possibly). Am I unreasonable to expect that messages sent to a particular audience should stay within that audience (I'm not expecting total secrecy here - just, if I sent it to adults, it was meant for adults).

If IABU then I will take it on the chin. I'm bloody not though.

[KaleSlayer]

I can’t imagine my kids being interested in what a group of mums are talking about. They’ve actually bothered to go into a group chat their mum is on, at age 8-10, and read the messages.

[ChampagneTastes]

The conversation first happened because one of the mums told another that her DS had taken a photo of her when she wasn't looking and shared it on Houseparty. This then led to "and we'd best be careful what we say as he reads all my messages too".

[BackforGood]

To me, this is similar to the other thread that is running currently, where a couple of posters say they would tell their dh / dp anything that a friend said to them, even something said in confidence or something wat was clearly private and personal.
A WhatsApp group is clearly for the people who are in the WhatsApp group. You can even check who is in the group (ie, who the audience is) before you post anything. It is completely wrong to show messages in any group to people who aren't in the group without checking with the other people first, or at least letting them know you are going to do that.
Surely everyone speaks or writes slightly differently according to their audience. Therefore everyone has a right to know who that audience is.