Feel like they made a mistake hiring me and that they'll realise it eventually (vent)

Feel like they made a mistake hiring me and that they'll realise it eventually (vent) So I'm almost done with my internship at a big firm and half way through they already offered me a job for after my internship ends. I told HR right then that I stutter and that it will probably never go away. They told me they don't mind but still... Everytime I stutter in front of colleagues I keep thinking about what they might be thinking. Basically I keep thinking that after a while they'll be sick of me or think I don't have a future in this line of work seeing I'll have to talk to clients at some point. Because of this I think I'll never be fully comfortable talking at the office. Just wanted to vent, thank you for reading :)