Firstly, you have noticed he has changed. Secondly, there must be something that has led to the sudden change. Thirdly, you don't know whether what he is saying is true. However, the change you've noticed is enough to sound the warning bells.
He wants peace the reason he broke up with you. You should give him what he wants. Don't contact him. You'll only be hurting yourself if you intend to try to get him back. It's time to move on. It's the best remedy.
You've been in a relationship for a lengthy period. It might be hard to want to move on. But you've to. You can't trust him with your heart anymore.