Depression Support Group
Depression is a real and debilitating condition that is often misunderstood by family and friends. Its meaning can range from a prolonged period of sadness to an actual mental illness with specific symptoms. Find and share experiences with others who are going through the same struggles.
You are not responsible for her happiness. That doesn't mean making her actively unhappy, of course, but you saying "no" to her is not an act of selfishness, it's saying "yes" to your own needs, which come first in this situation. You are not there to serve her needs.
Maybe in the future you will be able to find something with her. Maybe not. In the mean time you are entitled to grieve it, and then find someone else to be with.
Gentle hugs