You need to consider that this is mainly the fear of the stutter which has caused this rather than the stutter itself. People won’t react as harshly to the stutter as your fear is impacting you. This is where you need to be brave and face your fear and let that stutter happen. there are far worse things and you’re being mild you just need to put yourself out there. Maybe do voice chat online where no one knows you. I find that with my stutter comes and goes in waves and sometimes I have good confidence and that helps. Sometimes I’m less confident and that too has an impact. Put yourself out there and embrace it, it’s all you can do and everything will be okay.