I feel your pain. I was put on the spot to talk in front of my fellow classmates several times from elementary to high school and it sucked every single time because of my stuttering was extremely worse back then (btw I'm 20 years old and finish school back in 2016). Some advice I could give you to avoid another incident like that from happening again is to always take deep breaths before speaking to get rid off any tension and anxiety. Also talk slower then what you normally accustomed to and be confident when your speaking to boost your courage. Feel free to share this advice with others offline and online and message me or reply and tell by practising that advice if it helps or not.