Dude, what kind of messed up people do you work for? Hold your ground when people demote you and put you down like that. I know you need a job to survive, but have some self-respect Jesus. If a boss was to tell me sorry you're not fit for this role because you stutter, the first thing you do is walk out of that room and connect with an HR contact and discuss your rights and contract. You don't sit and listen to shit like that.