As the poison coursed through his veins the Doctor just wanted some relief. When the hologram flickered and changed he knew the extra pain was nothing to do with the poison and all to do with his own guilt and hatred.
Rose, oh Rose. He had abandoned her not once but twice, the same damned beach both times. She had loved him and in his past he had loved her, in retrospect that was probably the cause of it all. He had burnt up a sun just to say goodbye. She had jumped through universes to find him again. In the end he'd run, the same as he always did. Run away rather than face his emotions.
Martha, his wonderful Martha Jones. She didn't deserve what he had done to her. Martha was good to him, she trusted him, believed in him, even walked the Earth for him. But nothing changed. He was still too hung up on losing Rose to even give Martha the time of day. She left him in the end.
The hologram flickered again and the guilt doubled in strength.
Donna Noble. His best mate, the one companion who was exactly what he needed. Someone to stop him. He destroyed her life. Ripped out her memories and all the things that made her Donna, leaving nothing but an empty shell behind. It had broken his hearts to say goodbye, even now he remembered the look of terror in her eyes as she realised what he had to do and still it hurts. No, he couldn't face Donna again.
"Please, there has to be someone in the universe I haven't screwed up."