I don't feel like good friend material anymore.
Why don't you feel like friend material anymore?
I spend way too much time in my own head.
Many people have rich internal lives, but that shouldn't prevent you from being a good friend to others. Just because you spend a lot of time in your head, doesn't mean that you don't have a lot to offer friends. Try not to be down on yourself and consider what you have to offer as a friend to others.
It's fine, I'm not a good friend anymore.
I think you're being too hard on yourself. If you decide you're ready to be a friend, you can do it. Don't psych yourself out unnecessarily.