You can’t be friends. If he is contacting you like that while being so adamant on reconsidering options, means he has something else going on in his mind too. You said so yourself that you are much happier now that he is out of your life, then just ignore his emails and stuff. You can’t block his number or change your number but you can at least block his email, no? Don’t pay attention. Its all mind games to trouble you/pressurise you and force you to rethink. Ignore.