You are definitely not worthless. When I get unhappy about something, I always say to myself "things could be much worse" and it helps because there are millions of people who are living a much worse life. You have to count your blessings. My stuttering used to be worse, now I rarely stutter. I have some tips for you that worked for me. Do not be nervous. I know it's difficult to do but practice it, it will help a lot. Avoiding eye contact have also helped my stuttering. Also, take your time talking, practice on talking slow to yourself when you're alone. If I think of anymore tips, I'll let you know.