Happy New Year!! And I know what you mean. Sometimes you can't even explain yourself or even deescalate a situation because of the words aren't coming out for that either. Thing is though with stuttering, is that blocks normally occur at the start of a word or when you beginning saying a sentence/phrase. So in this case, you would block on the "i'. Since it's a vowel, you could try easy onset on here. So basically slowing down the sound, dragging it out on an exhale, making sure to apply as little pressure to the vocal chords. Which results in a very breathy 'i' sound. Now we all know easy onset and these speech therapy techniques are hard to use in real world scenarios, when speech is very spontaneous, but still give at go and practice using it in such situations even when it fails sometimes. You'll want to focus on very very very slowly gradually turning on your voice after getting your mouth in the position to form the 'i' sound. For consonants, try the bouncing technique while making sure you are using as little effort/activation when saying the b-b-b-b or t-t-t-t or whatever the first phonetic sound you were trying to say. Also non-verbals can work great in this situation. "I can't say the word" is just expressing frustration. And frustration can be conveyed non-verbally in many ways such as via an exasperated sigh, a shaking of your head (like you're saying no). These are just a few examples.