An issue

So, I have this friend. This friend is my best friend. Lately though we seem to be growing apart. I keep feeling like I'm getting "the shaft." I feel like my friend hasn't been paying attention to me. I feel like my friend doesn't talk to me and doesn't want to invest in our friendship anymore.
Granted, I also haven't been real great "friend" material. I've said things, I've put myself back behind my wall. The more unhappy I get the more I lash out. I'm a hard person to get along with.
What do I do?
Is the friendship important? Yes.
Is it worth saving?