Hi Nick - welcome here!
As you begin to apply yourself consistently within writing, self-forgiveness and self-correction you will start to stabilize yourself in terms of your recent discovery of the the deception of emotions. Indeed, it can be pretty shocking at first, when we begin to realize that we've been existing within an illusory bubble as just a character in our own mind-movie - thus, you will see how writing and self-forgiveness will be your anchors to keep you here, applying yourself breath by breath. Realize, you've always been existing within the fear you're currently experiencing, you've just created characters and developed coping mechanisms throughout your life to suppress the fear, to not have to face and deal with the fear, and now that you're beginning to stop and deprogram those points, the fear will SEEM more extensive - so take things slowly, step by step, it's going to take time some time to step out of character - so keep things practical in terms of your daily responsibilities, and allow yourself to discover yourself again in each moment wherein YOU decide who you will be, not the character - this definitely includes re-discovering yourself through music, and as such playing guitar can be a very cool physical way to ground yourself here, practice breathing and voicing yourself as a physical self-expression.
Also suggest to check out:Where Self-Honesty Begins