"Nothing," he said. "I don't expect you to forgive me. And I know that what I did wasn't okay. I just... I needed to say it."
Of all the things Barry screwed up in the past year, letting Patty go was the one that he regretted the most, even though deep down he knew that it was the only choice he could have made in that moment. Zoom was far too dangerous and had no qualms about going after the people who meant the most to Barry. And as competent as Patty was, Barry could barely take them out with all of his advantages.
"I'll stay out of your way," he said. "I know that asking if we can be friends is too much, but... if and when you feel like you're ready for that, let me know, okay?"
He stood, knowing there was no sense in staying any longer. Patty had every right to hate him for what he did and now that he said what he wanted to say, he didn't want to force his presence on her.