Hi,
Searching for a fault in an event and eventually find ourselves as a guilty one, has so many side effects such as depression, anxiety, stress, overwhelmed... Whatever happens, has a reason, as you forgive a friend for a fault, try to forgive yourself, it's a best solution. Nothing is more important than your health. Anything happened, was an experience... You are so young, you have potential to build a wonderful life. So forgive yourself for whatever happened.
A psychologist/therapist can help you in this path.
Am sure you will feel better after talking with a psychologist.
Please do take care.
Next Steps
consult with a psychologist/therapist as soon as possible.