I'm not going to send my ex back the rent money he paid
Why won't you send him the money?
He won't be moving in any longer and I already put the deposit down.
That's not very nice. You shouldn't keep your ex's money if he isn't even going to move in.
What is this, the 1940s? It should be his problem if he blows his money.
Who cares what year it is unless he signed a contract you need to give the money back. It is stealing, you know he can take you to court and you have to give the money back along with his legal fees right?