Little Missy;
I don't think it's unreasonable to be disappointed that your dad said one thing and did another. That little girl inside still needs to depend upon her daddy.
But, you make a valid point about protecting yourself. And I think the answer lies in acceptance.
You can continue to invite him to important days in the lives of your family. Just accept that he may or may not show. Accept what is for what it is.
For whatever reason, he could not follow through. I'm sorry for your pain over this, but, anger won't change it. Can you view him as being ill? Self absorbtion is an illness. I don't know if he has alcohol or other problems too. If so, you KNOW he's sick.
Protect yourself by having no expectations and by accepting what is for what it is. Others do only what they are able to do at the time, no different than you and I. And when they, (we), know better, we all do better.
Shalom!