You are absolutely right, there are always two people involved. And we are responsible for our own actions and they do affect people.
I just don't want to see him still going back and forth between you and her. If he wants to be with you, great, wonderful, he needs to tell and move on.
I've never bought the excuse people are not able to break up with or move away from the OP. Strange how easy they could move away from a marriage, but not from a girlfriend or boyrfriend?
Take care. You deserve someone who wants to be with you.
And no, it is rarely a good idea to dwell on events in the past.