I got Laughed at for Stuttering in Class.

I got Laughed at for Stuttering in Class. I've always had a stutter since I started to speak. I'm in high school still and I have a part-time job. Both of those have been going well so far. Good Grades, biweekly paycheck, having friends you get just of things. But my stuttering is now ruining that. At my job I have to talk to people and ask them questions which isn't difficult until it is. I'll be talking to someone and then my mouth just stops. I know what I want to say but It won't come out the way I need/want it or I'll just get stuck on a pause and in that moment all I can say is 'um' In school, it's worse. When I want to ask a question or speak I just get stuck on long pauses again. I feel everyone staring at me when it happens and again all I can say is 'um' and get stuck on words. But today was the worst, I was trying to say something about the topic that we were on in history class and when I started to stutter and get stuck someone laughed at me. It was loud enough that everyone heard it. In that moment I wanted to curl up into a ball and leave. I felt so humiliated. The worst part is that I know who laughed, and when my teacher asked me if 'I knew who did it' all I could do was just say no. I don't know what to do at this point. I've always lived with my stuttering but now it's making my Life harder. I'm hoping that the laughing will be a one-time thing but how do I deal with this?