I used to do it. After a particularly bad stuttering incident I would dwell on it and keep thinking about it, making me more anxious and then those suicidal thoughts would creep in. Try not to get caught up in this cycle and try to forget about it. Remember you stuttering or having a block or not having a fluent conversation with someone isn't the end of the world. Believe me people don't think about it as much as we do so be easy on yourself. After something like this happens try breathing excercises or some sort of meditation to try to calm yourself, this definitely helped me a lot.