I want to invite this girl out that my friend is crushing on her for over two years
Why do you want to go out with that girl?
she's a close friend of mine and she's special to me.
If your friend likes your friend  you should stay away from her. It's not ok to make a move on her.
She is my friend too and he has been so annoying about it.
If he has not acted on it and you also have feelings for her it is another story.   Just do it in a respectable way so that he is not hurt.