LMAO. create exchange. watch serious amount of funds come in in crypto coins. use excuse site got hacked. close site down. cash in on coins. What a way to rob people 
def ender, i hgihly suggest you refund all the money. you also lied, the password hashes weren't decrypted. they are hashed with SHA512, which is a one way hashing function that can't be decrypted.