@PinkTicker
YANBU. I would be livid. DH had form for doing this for a short time a few years ago - (and several of my friends partners did it too!) AND it seems, the partners of many women on here.
My DH used to think candid pics of me were cute - even when I was 4-5 stone overweight. I looked fat and slouchy and had a double chin, and looked 10 years older. He used to take the camera outside to take pics of the cats, and he would poke the camera through the kitchen window and take 'candids' of me, and even FILM me. 
I told him to stop as it's making me angry and upset. He minimised I and said I was being silly, and that I looked 'adorable.'
So I started doing the same to him, and took a pic of him, hunched over, with his pot belly hanging out. That ONE pic stopped him, and he was a bit sheepish and said 'OK I get the message...' 
Why do men not care? It's because men are not taught to the same extent to be so self-conscious and that physical appearance is the most important thing in life.
I do disagree with this. As I said, my DH was very unhappy and pissed off when I did it to him. I do know a few women whose men do this, even though they know their woman/partner is upset and unhappy about it. Is it some kind of weird control thing? Trying to make us feel bad about ourselves? I don't know.
Also, women don't tend to do it to their men. But I think if we did start doing it, men wouldn't like it either.
There's a similar story in the media at the moment. 'Arg' who dates Gemma Collins has uploaded a VIDEO of her snoring, onto the internet! She has apparently dumped him.
www.dailystar.co.uk/showbiz/762056/gemma-collins-snoring-video-twitter-james-argent-split-gc
By the way, I don't think it's possible to delete a pic from a group chat. Once it's been posted, you can delete it, but all the others will have it. All you can do is ask them to delete it as you are upset your DH shared it. Expect at least one person to keep it though!