Next time something like this happens look at the after effects.. Look at the unpleasantness of your state of mind.. in fact, look at the unpleasant feeling, say to yourself:"There is a feeling. There is a feeling." And then ask yourself:"If there is a feeling, I can see the feeling, am I the feeling? Or is it just a feeling and I am something else?" Then look at the situation as a whole and see that there is really nothing happening right now, there is only a memory of something happening. That whole unpleasant situation has come to pass, it is no more. See how thoughts are just thoughts, memory is just memory, feelings are just feelings. Ask yourself:"Can I feel good while there is a unpleasant feeling?". When unpleasant situation arises either connected with stuttering or otherwise use these three tools of investigation: Impermanence, look at the situation you have experienced and ask yourself:"Has this situation come to pass or is it still happening?" and don't listen to any answers the minds cooks up, just observe. Unsatisfactory, look at the situation and see the unpleasant feeling and ask yourself:"Is this thinking and memorizing bringing me any satisfaction?; Has this thinking and memorizing solved anything or has it only burned me more?", and once again.. don't listen to the answers your mind cooks up (the voice that is constantly judging everything), but just observe. Not-self: whatever I can observe is not me, is not mine and does not belong to me. Principle of Subject and Object. See if this helps..