You can't believe everything he tells you. However, you must learn to listen very, very closely and sift through the garbage that is coming out of his mouth. Some of what he says will be projection and then there will be some tiny tidbits that will help you to better understand how he feels, what he's experiencing.
Watch his body language....it will say it all.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.