Xanax is an anxiolytic, so it would definitely help you with your fear of stuttering, and hence maybe reduce your stuttering. But believe me, that’s no solution. It may help temporarily, but that’s all. You would have to take it every day (if you want the fear-reducing effect every day) and would become heavily addicted to one of the worst substances to be addicted to. Addiction to Benzodiazepines (the substance group Xanax and Valium belong to) is no joke. If you take it over months, physical and psychological withdrawal would be severe i.e. little to no sleep, panic attacks, dissociation ect. Just google Benzo withdrawal und you will know what I mean. It’s hell incarnate. Im not saying never take it, just be really really careful with it, and be aware that it will solve none of your problems. In the Long run it will worsen your problems. Real progress takes time and effort, there is no quick fix. I stuttered severely from when I was a young child into early adulthood, and I’m now (most of the time) completely fluent. If my stutter got better, yours can too.