how do i know

This is a way too general question. But the short answer is that he is doing "worrg" to you if he is doing anything that belittles you or anything that makes you uncomfortable.

On a more specific note, if he hits you in any way, he is doing you wrong and you need to get away from him FOREVER immediately.

Hope this helps. You'll get more responses and maybe even better ones if you can narrow down your question or give us an example of the behaviour you are concerned about.