Cancel/Stop Text Message When Attachments Freeze

Took a 20 second video with iPhone; attached it to a text message, and added additional commentary; pressed Send and watched the blue progress bar move from left to right, then stopping approximately 90% of the way.

Several minutes pass and status is the same. And yes, I was using a WiFi connection and not my cellular provider.

If the attachment was too large I would expect an error message. Otherwise is there a way to cancel/stop/delete the message or attachment? Everytime I go to text msg this person I see the same progress bar at 90%.

Thx