I think you'll get a ton of suggestions on the anniversary, but my advice is to stay quiet, understand that it's going to hurt, cry or scream or whatever on your own, and wake up the next day and realize it's still ok out there.
I didn't contact XH on ours back in Dec. and we were not divorced yet. Sometime after dinner, he texted me and just said something like "I realize that if I contact you today I risk hurting you deeply and making the wound worse, and if I don't contact you today, I look like a horrible person, so this is a no-win situation for me. Just know that I know what the significance of this day is and I hope you're with your family or friends right now."
That message hurt me so deeply it took days to recover. I'd rather he not have said anything.
So in my mind, you don't do anything. If she texts you or whatever to say "Happy Anniversary", you say "you too." Then walk away. If she doesn't contact you, you might be better off. I'm sorry you have to face this, but you can't celebrate something with her that she is smack dab in the middle of destroying. Celebrate your memories with your kids or on your own. Those memories are JUST AS IMPORTANT in the scheme of things even if she's not emotionally available to celebrate with you.
M45 Bomb 6/09; EA 6/10; Divorced 1/11 Proud single mom of 7 little feline girls and one little feline boy "Fall down 53 times. Get up 54." -- Zen saying