"Thanks for the compliments, I am taking steps to make myself happy and independent and I'm glad it shows. At this point, a romantic R with someone else is not one of those steps." Then, drop it. There is nothing wrong with you stepping away from the R, becoming happy with yourself, and him experiencing the emotions of you not being a sure thing anymore.
If he pushes it and continues to accuse you: "H, I have said what I am going to say here. I am unwilling to sacrifice my emotional energy further unless we both choose to begin an R on clear terms that we both want."
Don't try to reassure him or fix his confusion. They are his to fix. Just be direct and matter of fact.
