Well i can tell you one thing, your not alone. Far from it. What you described is almost exactly my life. I remember this traumatizing incident when i was a kid going into a new class in the middle of the school year and my teacher asked me to stand in front of the class and tell everyone a little about myself. I was already realizing there was something wrong with how i talked but being a 3-4th grader, i didn't know how to deal with it. I got up there tried speaking and all I remember is laughter and this sense of shame. I remember the incident clearly to this day. Now im 27, I dropped out of college, i did good in school for the most part considering i tried avoiding all the presentations, introductions, and in class reading. I ditched A LOT to avoid these. Then I pretty much sheltered myself from the world for a few years. Now its worse than ever. Its only within the past couple of years that im starting to break out and find help for my stutter. My advise, don't let it break you like it did me. Fight through it and don't be afraid to speak. The less you speak, the harder it is to control.