The problem reminds her of difficulties she had with her mother while she was growing up. Once she could refocus on the love and dedication of the professionals who work with her daughter every day, she was able to calmly and clearly express her thoughts which usually resolves the problem. While these are general considerations, I would recommend that you channel some of your energy into a parent organization, such as the Autism Society of America, or the ARC, or UCP, etc. Connecting with other parents who are either just starting out on this journey or further along can be priceless. You may also want to channel some of your intense feelings into an advocacy organization that helps other families.
Anger is part of the hurt.
Gaining perspective and learning how to be assertive helps to heal the heartbreak. It takes time and support. If nothing else, our special children teach us patience - with them, with ourselves, and with the world around us. I find that my skin hasn't toughened up as much as I would like it too when it comes to going out in the community with my six year old son, who has autism. I don't find it hard to tell people he has autism if he doesn't respond to their questions.