I’m so sorry this happened to you. These people are deeply unprofessional and sound like real assholes. Even though this is your dream firm, it sounds like it has a terrible work culture and hostile work environment, you may have dodged a bullet here - imagine dealing with that bullshit every day. Don’t let that get you down for your job hunt at large, not all firms will treat you like that. If you feel this is right for you, consider this: instead of following up with the usual thank you note, follow up with an email where you note the behavior of your potential colleagues, and point out to the interviewer/your possible boss that stuttering is a disability, and that you are “shocked and disappointed that such a reputable firm with an excellent reputation, known for (xyz) thinks it’s acceptable to let its associates mock people with disabilities.” Something along those lines. From the sound of your post, this is sounds like a well known firm in your industry, and I’m willing to imagine they, like many prominent firms/companies, will outwardly talk another their commitment to diversity and inclusion. Sending that kind of email will definitely hit them where it hurts - if they’re well known, they won’t want to have a reputation of being non-diverse or inclusive, especially now that a lot of due diligence job hunters do online comes from other candidates giving feedback about them online. I’m not sure how this would effect your chances for this position, but first, it might help you regain some power and dignity, and second, shame them as they deserve to be shamed. Trust me, well known companies/firms hate being called out on this bullshit because they worry about their reputations, and that would definitely hit them where it hurts. I’ve had to send similar emails, and HR and leadership/upper level management always freak the fuck out, and you get the upper hand.