Am I overreacting?

I should preface this by saying I have two kids and one on the way. My oldest is on the spectrum but very high functioning. I'm very passionate about inclusion for individuals on the spectrum and other special needs.

So I'm texting with one of my good friends and we're joking back and forth. This friend is a very close friend I've had for years and she knows my situation with my son very well. She also knows my hatred for derogatory language targeted towards individuals with special needs. So we're texting and my phone auto corrects to something else so the text I sent doesn't make sense. She then quips back by telling me to "stop acting mentally delayed". I told her that that terminology was offensive and she said it wasn't and I need to "stop being a snowflake" that there's nothing even "wrong with my son and I need to stop taking the special needs thing so seriously". I told her that even if I didn't have a special needs child I would still find statements like that offensive and she just sent a "🙄" back and that was the end of the conversation. I don't feel I'm over reacting because I feel casual statements like that are the reason that individuals with special needs are so routinely discriminated against. What's your take on this?