The Doctor didn't need to see - the Master's reaction was all he needed to know. It was just as he predicted. "Would you rather I lied?" he asked.
He suspected that if he tried to go up to him, the Master would only pull away, so instead he wandered over to one of the seats near the railing and plopped down, setting the journal aside. Then he started monologuing, just speaking out loud in a casual, stream of consciousness sort of way. And whether the Master listened or not, the Doctor left that up to him.
"I had a companion. Clara. We met... well.. she knew me from my previous regeneration, the one just before my current body. She was a bit of a bossy boots, but she was still flirty and fun. But after I regenerated... she couldn't see me, she didn't accept this new face, or understand why I looked older. Angrier. It was the worst feeling I ever felt in my whole life, that rejection. It still upsets me, thinking about it. She eventually accepted, but the damage was done. We never quite interacted the same way again. I feel the same way with Rose. We tease and joke, but I know in my hearts that she's much more attached to Hair Gel, and Leather Jacket before that. I even kissed her while I was here." The Doctor shrugged. "It wasn't the same. I guess it takes a very special sort to see past the bodies, but I'm pretty sure even River has her preferences. Funny thing though." He paused to scratch his nose. "When I looked into Missy's eyes? I saw somebody else looking back at me."