How can I overcome my fear?

I live in Rhode Island and tornadoes are very rare, but I'm absolutely terrified. I have been since a tornado warning not too long ago. I realized how much I really love my life as I thought I was going to die. The tornado ended up not being anywhere in our state, but my dad was driving home right near where one hit. Ever since I have not only been afraid of thunderstorms but I've been unable to sleep at night because I'm so afraid of dying. I actually used to love them and enjoy them, though I had been afraid of them for a very long time. I know everyone comes to the realization they will someday die, but how can I learn to deal with it? Worrying won't change anything or get me anywhere and I'm only making myself sick missing all these hours of sleep.