Sorry to hear abt your problem brother. Perhaps get some legal advise then if possible lodge a police report abt it. Worse come to worse, approach MCA or DAP to ask for some advise(mostly legal i suspect) over your issue.

In future, just avoid meeting him altogether to prevent problem. Change your cellphone/contacts/email etc. My family had a relative which back-stabbed us before in a business. Though we won in the court case, we never even spoke since after that.

I think revenge is very pointless at this point. Cessation of any contact of him is the best option.