People don't know what to say/ how to say it and just want to be helpful. I have had several things said to me that "upset" me. I very soon had to accept that people say things without knowing what they're really saying. I can guarantee I've done the same thing when it comes to someone else facing a challenging situation.
I hear your frustration - and recognize that I have frustration too. However, I think the best thing you can do is breathe in and breathe out and keep on keeping on.... realizing the person thinks they said something helpful, not harmful. Don't give them the power to question what you believe or how you feel. You keep on with your positive attitude!!