Management can make or break a position, which it seems like every superior you had was a grade A douche. I’ve had my challenges while finding and procuring employment, but nothing to that extent. If you had evidence (emails, recordings, etc) of the discrimination, you most likely could’ve done something, at least. My recommendation would be to try to find something in government. While it may not be the most exciting or enjoyable type of work, it’s easier to get in and be promoted even if you have a disability such as a stutter.