"You are right." Severus knew Lily was right, would he have been alone he would have left probably after some revenge of course. "We will stay."
Reluctantly he moved away from her, he took a steadying breath and offered Lily his hand. He would show her that her dance lessons had been successful. "Will you dance with me?" He usually didn't like to attract attention to himself, attention usually meant being bullied or being made fun off. He did remember the way Lily talked about going to a ball though, this was not a proper ball but probably the closest thing to it he would ever be able to take her to.
It might seem like denial but he was going to put this Harry-person out of his mind for a bit. He would deal with the future and the fact that obviously he was not the the one marrying Lily later... hopefully much later.