On the coat rack. It's slightly off, though :p
Anyways, here's what I tell anyone on this community who's feeling depressed, as after recovering from an endless string of sadness and regret and inability to cope with things healthily, I have a bit of experience.
You need to relax your mind. You cannot consciously say "I am going to stop thinking about ____." Go out, enjoy life. Become comfortable with yourself. You must come to terms with whatever is hacking at your mind. This can be done through creative outlets, or some introspective thought.
There is danger in introspective thought. If your bad memories, those bring you so much pain that you block them out, are powerful enough they will drive you insane if you reflect on them too much. You will try to block so much that eventually the pressure will build up and the dam will break.
Your recent detachment from someone close to you is bringing those bad memories up to the surface: so much so that they are threatening to break the dam. You need to let the pressure out, either through poetry, meditation, hanging out with friends, going to a bar, going to a party, driving a far distance, running, working out, hooking up with a damn fine girl. You need to let enough pressure out so where you can say "You know, I kind of like what I've become" and then you can start climbing. The more good you experience, the more you can say "Well, the past was awful. But hey, I can still have fun! After all that shit, I can still have a good time."
You need to have a damned good time. Some of your best times were probably with her. But you need to understand that you can have wonderful times without her. Don't reflect on how much more fun it could be with her.
Just lose yourself in the moment, don't think about anything. Just have a good time. Enjoy life itself. It's hard, but it's doable.
It took me a long time to see fun in life. I don't think I understood how important fun was until a month ago. How important it is to take your mind off of everything, when you don't need your mind to focus on anything. No, it isn't good to do that all the time. But your brain can be
exercised and improved, just like everything else in your body.
If you're part of this community, you know how important knowledge is. I have something to tell you: experience is just as important. Having your senses stimulated, through the taste of an amazing meal, the breath of fresh air, the adrenaline rush of winning a competition, relaxing and talking with friends, is one of the most important things in life. Knowledge will simply help you understand the experience.
Life, all of life, is experience. You experiencing sensory input and reacting to said input. Instinct, past experience, your brain's hardware, will tell you to do something. Logic will show you multiple ways to react to it. It's up to your past experience and all the knowledge you have accrued to choose the best path, for there is an infinite number of paths you can take through life.
We make mistakes. We experience bad things. It's important to know that bad things happen to everyone. The universe is chaotic: it is the antithesis of order. It is an extremely chaotic soup of particles that all interact with each other in ways that will only be detected with the finest of measurements, and when they are measured everything has changed again.
It is important that you understand they do not make life. They are a part of your life, obviously a large enough part of your life where you don't see how there could be any good.
If you don't have any confidence behind anything,
take a genetics test. It's a weird suggestion, but having confidence about what you are at your most basic level is more comforting than anything else. To know where your ancestors are from, what DNA makes up your body, is such powerful knowledge about your very existence that it should give you enough of a boost, a push.
As humans, we are all cousins. As humans, we are all distant cousins with all mammals. We are cousins with every organism that evolved from that one ancestor, that bacteria that formed from amino acids (or came on an asteroid from some other planet). All of life on Earth has a bond, one that can never be broken. That thick bond of our blood, our very DNA. Every person you see, every animal, every plant. We all are related to one another. We are all branches of one massive tree of life: that is the most powerful bit of knowledge I get from evolutionary theory. (I'm not sure about Domains though. We may not be related to certain bacteria.)
Come back to life, cousin. It can be painful. Incredibly painful. You must understand that there will always be pain, there will always be chaos. That pain gives contrast to the beauty of life. A stranger helping someone across the road, a father walking through the park with his son, a group of people gaining freedom, a couple making love.
You have a great life ahead of you. One that will have many bumps, and much pain. It will also have great beauty, and much happiness. Think on the happy times when you are sad, and let them remind you that you can have fun in the future. Most importantly, have fun. Life is a finite amount of time. Enjoy as much of it as possible.