Is it illegal if my boss doesn't send me a text message to threaten him?

It is illegal for the boss not to pay wages in arrears. In this case, you can report and prosecute to the labor department or the court according to law, which can only be solved within the legal framework. It's illegal for you to send a text message threatening him and leave illegal evidence for the other party, so it's a bit complicated for you to default on your salary again!