Is it normal to be scared by the thougt of eternity?

"You" will never spend eternity anywhere. The "you" that I am referring to is your consciousness. At the time of death, your consciousness will cease and there won't be any "you" left. The matter and energy that makes up your biological matter (which is the source of your consciousness) will be redistributed. Energy will be released in the form of heat. Matter will break down into simpler molecules due to decomposition. Before you were conceived as a fetus, your consciousness did not exist. This is why you have no memory or record of times before your conception. Death will be the same. You needn't worry about anything. With all that said, however, I must note that your fears are normal. This is due to the overwhelming prevalence of religious myths amongst us humans. These myths seem to be derived from the fear of death. However, I think we can all see how these myths have led to new fears, including your fear of "eternity". Just accept that you will die and that your consciousness will never experience any kind of eternity. When you're dead, you're dead.