He's a very stupid man, isn't he?
All his childish little digs... not nice, but ultimately - constant reminders of what a gigantic steaming bellend he is. And how much nicer your life is now. Without him. When all you have to do to not hear his carping voice any more is hit 'delete'.
You could email that to him, as suggested above. It would crush him and make him utterly FURIOUS with himself, though of course, all you'd get is abuse in return - the usual cover-up for his frustration and impotency.
Or you could start pointing out the glaring fact that all his snarky comments do is reinforce his inadequacy and the reasons why you left...
Him: 'Blah blah pickup at 6 if you can manage to do that given your bad timekeeping...'
You: 'Thanks for the info :) Hope you don't mind my mentioning it, but once again, you seem very preoccupied with me and getting a dig in! I do understand that you're still angry, but not sure that showing it so clearly is the best way to go? You just look as if you can't move on. Sorry to have to mention it and I do wish you all the best :) '
And similar, to every email:
'Thanks for the info :) Sorry to see that you still feel so upset by everything, hope you feel better soon.'
'Thanks for the info :) Sorry to see you are still brooding, had you thought of counselling? As ever, I do wish you all the best'
'Thanks for the info :) Did you look into counselling? It does sadden me to see you still so bitter and I really hope you can start to move on soon. All the best as ever :) '
'Thanks for the info :) Hope you feel more secure and positive in your life soon. All the best'
etc.
etc.
etc.
I give it a month before the nonsense starts calming down. And the best bit of this? If he starts on you in return to any of those emails, he simply proves what you are saying... and your email in return to the 'How dare you' only needs to be the email equivalent of the head tilt and 'Oh dear - I do seem to have touched a nerve. Let's not mention it again and I hope you feel better soon...'
Ah ha ha.