After a breakup, the smartest thing to do is to get rid of all of the items he ever gave to you because it will help you feel better, and at the same time, it will make him feel bad about himself.
You can pack up all of his things and leave them in front of his doors or deliver them by mail.
When he opens the package, he will recollect all of the past moments when the two of you were together, and it will strike him right into his head.
He will feel utterly sorry for not being there for you and for failing as a man to treat you the way you deserve.