Having trouble remembering a book I read on a girl surviving by herself after a nuclear accident?

I had to read this book for English class in I think 1998... it involved a girl surviving a nuclear explosion... her whole family died and she managed to survive but then this evil guy came into her town and basically she had to fight him so she could live. I think in the end she won and she took his radioactive-proof suit. This book was really miserable but it stuck in my mind all these years later. I really have no idea how to search for it, I don't remember names or anything. Thx for any help!