unfortunate / enemies from the past

"feelings that come back are feelings that never left."

Tracy is a stressed college student that has never felt more lonely. She changed her ways into becoming a new and better person, for herself and for the others. One day while she is grocery shopping she sees her old middle school classmate, he was more than just a classmate, she was his death enemy, and so was he, hers. Yet she cannot deny the feelings she "had" for him at that time as well. But the moment she sees him again she feels something strong she hasn't felt in so long.