First of all try not to sabotage yourself with all those thoughts; self-confidence is one of the keys to do well in interviews, focus on that. Also disclosure your stutter and try to make it look like an advantage: talk about how that made you more emphatic, humble and hard working so you think you will do very well in that position. In case you don't get this one, don't bash yourself (it happens to everyone, even to non-stutterers!); keep working on that and try to get a disability certificate because that will make you more employable. Best of luck!