I am very sorry to hear that you are feeling the way that you are. But please rest assured that help is available and that there is an answer to your experience of human selfishness. Let me also encourge you not to do something foolish but find someone you can talk to, someone who can help you talk through your feelings of loneliness.
Your observation that humanity is selfish is true. Everyone, everywhere, live for themselves in one way or another. In the opening chapters of the bible God is describes as the one who, not only made everything we see, he also made us. More importantly he made us for a purpose - to live in relationship with him. Because of this we owe him our allegiance. We should honour him and treat him like God, listening to him and live as he wants us to live. His desire is that we love one another and “do to them as we would want them to do to us”.
However, humanity, on the whole, ignores God most of the time. We want to live our lives our own way without reference to him. We rebel against him and don’t want him to tell us what to do. This is what we call sin. Rather than living for God and each other, we live for ourselves at the expense of God and other people.
This is where our selfishness comes from. The problem with this is that everyone, including yourself, has rebelled in this way. No matter how hard you try, there is an element of selfishness in you as there is an element of selfishness in me.
This rebellion makes God angry and leads to a breakdown in our relationship with him and each other. God will punish us and there is nothing we can do about this. So God does something for us instead.
Because of his love for us God sent his Son - Jesus - to show us how to live and to die in our place, taking the punishment for our rebellion, so that we may be forgiven. He did not rebel against God and was not selfish like the rest of humanity. Rather he served us by giving himself up for us so that those who put their trust (or faith) in Jesus and what he has done can be forgiven by God and reconciled to him.
How does this help you?
Well first it helps you understand why people are selfish - including you and me. We are, by nature, selfish sinful people.
But second, it also shows you that this is not the end of it. God does not want you or me to live this way. He wants us to turn back to him, be forgiven and given a second chance at living life for him.
Finally it shows us how to deal with other people’s selfishness. God’s willingness to forgive our sins means we should be willing to forgive those who wrong us.
Rauf, I don’t know exactly what your circumstances are but I do know that, like me, you need to be forgiven by God. As you experience the joy of being forgiven by God, so you will see the need to forgive others and help them come to the same understanding about God. This is the best way forward for you.
Please write back to me if you have further questions.