Amy, I LOVE your pic, btw. What a gorgeous bunch you are.
I'm sorry about the PMDD.

Have you looked around on the Internet for info? There's a site here:
http://www.drdonnica.com/display.asp?article=1086
I don't know if you're taking meds for depression, but it looks as though SSRIs are something that should alleviate the symptoms.
I used to have terrible mood swings like yours until I started just acknowledging when I'm pms. I used to think, "This is crazy. Pull yourself together!"
Once I've acknowledged it in my head, I give myself some leeway. That might mean allowing myself more "me time", stepping back a bit from family-related activities, or just saying, "I'm going upstairs to have a good cry."

I know that sounds ridiculously simple, and I have no doubt it won't work for everyone, but it's helped me enormously.
I hope you get some relief soon, sweetie.