First of all, HAPPY BIRTHDAY!!!

How hurtful this must be for you. The only advice i can offer is; you cannot control the actions or words of others. I do not know the history between you and her, but grieve over her hurtful comments from today, and then *try* to remember that she must be suffering somehow, someway, herself, in order to make her child feel horrible. Then remember you do NOT deserve to be treated poorly, and try to allow what was said to be HER problem, not yours, if that makes sense?

I know, easier said than done. But its worth a shot, and your first priority needs to be your mental health, so try your best to imagine picking up her hurtful comments and passing them back to her, and walking away.. of course, this is coming from someone who finds visualization useful. lol