"Of course, it was, and I had six years to change your mind, but I couldn't afford to lose the Gryffindor's support." He needed their outmost loyalty and trust. It was the only way to convince Harry to do what needed to be done. He had no regrets about the outcome, though.
Albus looked at Draco over his glass and smiled. "You use his name. That is good to hear, almost as much as the fact that he's just a boy. Powerful and smart, but just a boy. They tend to do all sort of irrational things without thinking about the consequences. You must remember that."
He rested his hand on Draco's shoulder and squeezed it gently. "Now it's not a time to regret about mistakes you've made. You must use the time you have, and not dwell on the past. There are plenty of people looking for a cure from what Harry as said."