One of the hundred books a year I read:

Disaster threads through Dylan Moran’s life with the loss of his parents and his best friend. When his car plunges into a river, he frantically dives to save his wife from the trapped car, but also faces his doppelgänger standing on the bank and refusing to help. Confused and grieving, he runs into the mystery man a second time and discovers he is on a murder spree. Desperate for help, Dylan reaches to a psychiatrist, who claims he is her patient and that she can help him visit parallel universes where his outcomes are different.