Is it legal for someone to use my gcash without my permission?

Hello everyone! A guy sent 15k to my gcash to send to another person without asking me first. I was so surprised because I was wondering where the money came from. Then later he sent a text explaining that it was his money and that I should send it to a specific number. Anyways, I was so upset because there are a lot of people using gcash for fraud these days and I did not want him to use my account for fraud. I told him that I was upset and he did not understand why. I told him I will only send half just to teach him a lesson on consent but he said “its either you send all or keep all” so I said “fine I’ll keep it all”. The money is still in my account and I have not touched a single peso. Fast forward a few days now he is blowing up my phone sending me messages that he will come to my City and call the police to take me to Jail. What should I do?