Mine only let me know if he read my email when I say something that seems to strike a nerve like " How his behavior showed me the type of person he really was and that he didn't deserve me and that he lost me since he let me go" I was surprised that he answered so suddenly and upset. But why, if he doesn't want me?
You've answered your own question. You struck a nerve. Insecure attachers still have feelings, usually that overwhelm them into rumination or shutdown depending on how anxious or avoidant they are, and poking someone's ego and feelings of shame may trigger them. But why are you still "poking the bear" so to speak after the break up? Why not respect the breakup, respect him, and respect yourself?