time travel

Trying to fully comprehend the concept of time travel as it is layed out in this novel gives me what my husband refers to as "tetris brain". If anyone has ever played way too much tetris in one sitting, they know what i'm talking about. This guy, Henry, travels back in time, sometimes visiting his past self, hanging out. His body disappears from the present. It makes me wonder how many of him can time travel at once. This question has not been addressed in the book yet.
I just read a scene where his 38 year old self visited his 28 year old self. His 28 year old self was jealous of the older self because he was already everything that he was and more. Henry was concerned that his wife, Clare, (who is accustomed to his frequent disappearances and appearances) would prefer to spend time with his older self because they know each other better. He has been visiting her since she was 6; he was as old as 40. What would you do if you met your older self?