Self-acceptance is the absolute key. The more you avoid speaking and keep beating yourself up about the way you speak things are never going to get better. If anything, they will keep getting a lot worse. Shitty part? It's not easy at all. It takes a lot of time, effort and above all help. Like damn, I've been stuttering for 10 years because of an emotional trauma and I still avoid speaking a lot of times. I managed to go from a severe stutter to a mild stutter in 5 years out of those 10. Sometimes it gets severe depending on how confident or calm I'm feeling. It's never easy, but you gotta try.