Having dealt with a few people like him before, I have found that you really have to know your boundaries and never let people cross them. And also never let them talk down to you and insult or humiliate you. And if they turn violent, your have to walk away and ignore them.

I'm sorry you went through that! But you're 100% right and how I have managed to protect myself and surround myself only with good people after trauma. I think disrespecting boundaries is the first red flag for most abuse. Pleading, guiltily, bargaining etc to get you to relent on your original boundary, no matter how small. I so wish more people were aware of this. And to be clear it's not every time a person does that but I am definitely taking it into consideration with a critical eye especially if it becomes a common occurrence.

Another thing is be very aware of how they treat or talk about others, or what other people say about them. I can't tell you how many times someone in my life would reply "well they are always nice to me" about a jerk that they would eventually also be burned by that jerk. How they treat others you WILL eventually be the recipient of.