Don't respond until you get more advice here, Rain.
I know some things are true:
1)He was happy with you and can be again.
2)Don't accept his blame that it's all your fault. Maybe you could say "I hadn't thought of it that way." That acknowledges that you've heard him, without agreeing with him. Or maybe "I appreciate you being so open and honest with me."
3)Or this might be a time to say, "I'd like to respond to you when I'm feeling a little less emotional about this."

Remember, no begging, pursuing, crying.

11/4/15 W revealed EA/2 months later became PA with co-worker
Reconciling since late April 2016
Don't give up until it's time, then move on
Be patient, strong and kind but never a doormat