Breaking up with someone affects the brain ... it like an addiction. Don't feed the addiction with obsessively thinking about him. If you don't give it space in your brain then you will get over it quicker.
Forget about the money... its a tie. Go no contact. Change his contact name in your phone to DNA (do not answer) or block entirely. Tell your son, friends not to talk about him. If you see him in public go the other way.
He is not relationship material. period. Move on and you will get the relief you are looking for sooner.
Have you found an alanon group yet? Hugely helpful to me. Good luck.