I have no clue how to cope anymore.

I've suffered from depression and anxiety for a long time. I was diagnosed before I was even in middle school, and I tried many medications before giving up and trying a more mental approach. I've gotten by for years just on a fake positive attitude, hanging out with friends, w/e. Until I met my fifth, and last girlfriend. Have you ever met your definition of perfect? Because I have, and I wish I never had. That's the simplest explanation for how I feel about her. I tried so, so incredibly hard. Dating her, I became a completely different person. Happy, successful, outgoing. I tried absolutely everything I could to express her meaning to me, in my small world. She left me two weeks ago. I'm out of my "coping mechanisms". I failed.