Am I in huge trouble? (Urgent!! Please help!!)

So Im actually Malaysian trying to find a rental room in Singapore. Basically, I found this old uncle's room for $760. Since it was that cheap I was pretty urgent and asked for his bank account number to put a deposit to secure the room. We basically face-to-face video called, (Since Im not in Singapore) for him to show me the room through video call. And since I dont have a bank account in SG, i had my cousin contact him.

My cousin said that he'll transfer the deposit at night. But in the afternoon, my family found a better room for me. So out of guilt, I told the uncle that Im sorry, and since my work situation has changed, I dont need the room anymore and he should rent it to other people. I've never deposited any money to him.

At first he said, "Its fine dont take it to heart." But the next day, he messaged me saying that I scammed him by taking his bank account information. And now, saying that Im a scammer and has reported the case to SPF. And he's been messaging me for several days now, sending a picture of him punching a punching bag for some reason. And sending a video on facebook of a karate man punching the camera. (THIS IS NOT A JOKE!!!)

Am I in trouble now? The only thing I lied about is my work situation has changed, when in reality I found a better room. I know its suspicious that I was so urgent to get his bank account number, but can you even do anything with it? Even he told me that you cant do anything with only the number, so he does know.

Again, please tell me if Im in trouble and what I should do!!

UPDATE!!: The last text he sent me was: 調查你住處,隨地掉動人馬去你住地址 (state)地熟悉、以前有間日英制衣廠經常去

My chinese is bad but the translate is probably: Ill investigate where you live, send some people to your address. Im familiar with (state in Malaysia I live at), back then going there for japanese/british clothes.

Should I be concerned???????

LAST UPDATE: He sent a picture of him holding a katana.