Of Time and the Dreamer

Through a complicated and controlled experiment, Tyler Grant is able to visit his own past three times by traveling through his dream corridor to a small Illinois college where he was a student and later an instructor. The first two trips go without flaws and he is able to interact with a woman with whom he had been involved in an extra-marital relationship at the time. The only harm is to his emotional state upon interacting with her again. The third trip to another time in his past is because of a deadly auto accident in Atlanta that leaves his physical body in a coma. The dream corridor, discovered by experimenter Dr. Craig Marsh, actually takes Tyler (and other time-travelers, it turns out) to the past in another dimension. However, this third trip leaves Tyler on his own beyond the reach of his controllers -- Marsh and Estra Gudren, the former love interest who influenced his coming to Atlanta to teach at the college where she has been teaching since she left Illinois. He is trapped in his past in graduate school in southern Illinois.
Tyler soon discovers that he is not alone as a traveler. He is joined by a lovely Malaysian grad student who had inadvertently been caught up in his dream corridor because of his attachment to her at the time. She is the one who got away, and she is now joining him because her husband was kicking her to death back in Kuala Lumpur. She, Lalitha, is understandably confused because she remembers Tyler from 14 years ago in her own world. This is now 1983, not 1996 as it is in their own world.
Further complicating matters is the fact that she is kidnapped by a sociopath who has also traveled through Tyler's dream corridor. He appears to be Nolan, a photographer in Atlanta with whom Tyler had been working on a multi-media show. The relationship between these two former associates is quite complicated, we learn, particularly since one of his associates or one of their wives may have caused his auto accident.
Tyler discovers that he cannot avoid making changes in this other version of his past life, not only because of Lalitha and Nolan but also because Estra is able to travel through the dream corridor with Marsh's help and join him in the university in southern Illinois. Four time-travelers converge -- each of them able to change the past. But remember. This is another dimension, and whether or not they are ever able to return to their own world may be something beyond their control.
The story is told from a male and female point of view -- Tyler's (third person) and Estra's (third and first person). At the end, Tyler must involve himself in a dangerous struggle for Lalitha's sake in an area of stone known as Titan City.
If you could make changes in your own past, even if in a duplicate past in another dimension, would you do so? Would you try to avoid mistakes from the first time or re-live them?