Please stop berating yourself. You are not worthless. You are depressed. Of course you feel wretched. It’s how people who are depressed feel. Since you report that you have a loving, supportive family and good friends, chances are this doesn’t have much to do with your relationships. It’s likely there is a biochemical disorder contributing to how you feel.
Use your computer to identify sources of psychiatric help in your country. If there are none, or if they are hard to find, talk to your medical doctor. Your doctor may be able to prescribe some medications to improve your mood and to calm down the spinning in your mind.
Ideally, you should also see a mental health counselor to help you develop new coping skills and to help you move forward in your life. If you can’t find a counselor, I suggest you read the book Feeling Good: The New Mood Therapy by David Burns. Dr. Burns offers an excellent explanation of depression as well as practical strategies you can use to help yourself.
You may also find it very reassuring and helpful to join one of the forums here at PsychCentral. The forums provide a place for people who are not professionals to give each other support and advice.
I wish you well.