I remember your story... It is definitely a good idea to take responsibility for your actions, and to express it if he is a decent person. But please be careful not to turn it into taking his wrongdoing on yourself also just to be able to reconnect and find out more. I know it can be hard to see where one ends and the other begins, but if I can say only one thing: think twice, three times, and more, before you decide to get back into communicating with him and especially seeing him again. I did that with a very ***ed up, self absorbed T, and nothing good came of it in my case, except prolonging a useless obsession.