First of all, you have yet to prove God doesn't exist. All you have said is that you don't like the idea of God. How can we be happy in heaven when people are in Hell? Simply because we won't think about them. Why? It may sound aweful, but you have to realize that those in Hell chose not to respect God: they spent their lives ignoring Him and dissing Him. So why ought He purpetuate their memory? They don't deserve to be remembered.

As to why "good" people go to Hell, it is essential to realize that no one is good. Matthew 19:17 says that there is only one who is good: God. God is perfect. Our sin has blemished us and takes those things which we do that seem "good" and blemish them as well. Even when people do things which are "good" and even for the right reasons, it is because of the fact we are made in God's image-kind of a moment of being like Him. But unbelievers are uncapable of doing the right thing consistently. No matter how hard they try, they can't do it. The unbeliever can; this doesn't mean it will happen, however. At any rate, it is the sin of the person that sends them to Hell, being as they have not chosen to accept the atoning sacrafice of Jesus Christ.