How can I stop being afraid of saying words that I think I’ll stutter on?

How can I stop being afraid of saying words that I think I’ll stutter on? With certain words, I tend to say it ok when alone but when with others, I will tense up and I can feel the fear in my head when I think I want to say that word. I’m scared of moving my mouth then. How I do stop fearing it? How do I get over and overcome this fear? In the moment, I’m scared my mouth looks strange when I say the word. When I look in the mirror and practice to see, it’s doesnt look all that bad but in my head it feels like I’ll be moving my mouth strangely. How do I de-sensitise myself to the fear?