I've become a shell of myself
What has caused you to become a shell of yourself?
My best friend died last year and I haven't been the same since.
It's understandable that you are still going through the greiving process. You have recognized that you are not being your true self and it's okay to seek out support to help you through the greiving process. Getting support will help you to find the strength to return to yourself.
I can do it on my own. Grief is good for the soul.
It seems like you aren't successfully dealing with it yourself. A professional can help you make it through in a more healthy manner. You don't have to push through pain on your own.