Are you trying to minimise his insecurities, or propogate them? His insecurities are not about you. They are about him.
Talking about 'what you might have allowed if #### existed', and him getting mad over the answer is a ridiculous situation for any person to find themself in. And catering to such immature behaviour isn't going to help solve the problem.
By the way, I don't think he misunderstood your answer - rather, I don't think you understand the nature of his question (which was a hypothetical about an alternate past for you), or his anger (in response to your answer - but something that never actually happened), nor the insecurity that would cause it to arise (which is all about his issues, rather than yours)
Don't buy into this sort of world. It's toxic to him, and it's toxic to you.