This one is going to be hard for you I know. But, bottom line here is that you are going to have to learn to manage yourslef before you can manage you life and you finances. Some call it "Greed" others may call it "Selfish". Either way it has to be controlled. It is already controlling you.

You have to care for yourself above all. However, being indulgent and ignoring friends/not paying them back may unfortunately cause you to lose some of them. Here is a solution that may work for you and that I know has worked for me when I had problems with money in the past.

Every paycheck you get, take half of the money and put it straight into a bank account that you will not allow yourself to touch for fun things. Take the other half of your paycheck, and make it your reward for working so hard. You can use it to buy your guitar, go out to meals with friends, and do whatever you want with. That way you still have a reasonable amount for fun, but when it comes time to pay bills and pay friends back money that is owed to them you know you have it in your bank account and you are secure.

I hope you start to feel better soon; depression is a very hard thing to go through. You can get through this. If you need anyone to talk to, feel free to keep on posting here or PM me.