Sounds like BIL thrives on attention, so as long as you don't give it to him, you're probably okay. You don't owe him anything other than the apology you sent. Naturally we want to be respectful and not cause trouble, but sometimes it happens, and you have to deal with it. Let this be a lesson when it comes to emailing feelings!

This man sounds like he has a narcissistic personality disorder. Does he have any good qualities? Sometimes we call adults "big babies," when in fact they are either mentally ill or suffering from a personality disorder. If that's the case, there's not much you can do if he refuses treatment. Sounds like he has a hard time recognizing his own weaknesses. I say keep your distance and refuse to engage in a verbal volley should you cross paths with him again.