There are a thousand cliches that could be said and you covered a lot of them. Loneliness, depression, abandonment, despair, and frankly just the way our f’ed up brains work can make life just unbearable. I can’t give you some golden piece of advice, there isn’t one. I will say that no one knows the weight you carry, but we can certainly support you as you carry it. As for your friend that you have lost. People will tell you to move on. If she is important to you, then she is worth your efforts. Those efforts might be in vain, but abandoning it will only fill your life with “what if’s”. I am not saying you pursue or sacrifice all of your other things in your life to correct this relationship and rebuild this person, but to hopefully find a way to be even a small constant force in her life. She might reject, run away, or be angry, but you might be the person that saves her from herself and through this you might be the person that saves yourself along the way. You have a long hard path, one that I have walked and continue to walk. It is harrowing and easy to backslide. Just know that there are people who care, even if it is just some random person from the internet.