Just stuttering when angry. But why?

Hey!:)
To make it short: I normally never stutter or anything in that way. At all. Okay, sometimes I stop talking to consider what exactly to say next, but actually I talk really fast and fluent most of the time. No matter if I'm nervous, exited or ANYTHING, really. The only time I start stuttering is, when I'm really angry at someone/something. But every time I then try to let that anger out and start a practical I-hate-you-so-much-right-now speech I can't even get one sentence out, because I always suddenly start to stutter.
It's really bad in that moment, because either I stop talking before someone catches up to my problem in that second, or I'll get my point across, but fully emberess myself in front of whoever happens to be near me at that time.
The really bad thing is, that I actually only start getting this angry when someone starts blaming everything that goes wrong with anything on me. And it's kinda bad, when I can't even answer them in that moment and just have to listen to them rambling about how I'm to blame for everthing, because - if I did open my mouth - I'd stutter so much in my rage, I wouldn't be able to form even one sentence without needing at least 5-8 minutes for it. (And there I'd just get to say: "It isn't my fault, if you can't even do one thing on your own!")

I didn't really found any pages that could tell me about it, so I though maybe you could help me.
I have just two questions:
1. What could cause something like this? Why do I start stuttering like crazy only when I'm angry while I could really possibly talk steady during the end of the world?
2. How can I stop this from happening? Or will I always have to sit there, letting people hate-talk about me, while I'm unable to do anything?

I'm thankful for any answers, help and information.

-Silence