There's no way to edit a message once you've sent it if you've made a mistake. The 'unsend' is good but there's a problem, a recipient can see you've 'unsent' a message with the faded notification both ends. Can you make it so a recipient can't see you've 'unsent' a message? That, or bring back editing? Some of my conversations look a mess with lots of 'unsent' message signs. You can 'remove' them but it's still there their end. It's awkward 😳