One trick that helped me is that psychopaths tend to frame things in an either or, where the either is, you do what they want you to do, and the or is, you are a horrible person.

When you find that yourself in that situation, always pick the horrible person option.

What they think of you doesn't fucking matter.

Once they realize that they can't manipulate you, they'll get bored and move on.

I wish I could remember where I read it, but I do remember reading either an article or paper that laid out that when people are victimized, other abusers tend to be able to spot that somehow. Something about body language and it's all subconscious.

I don't have the answer here except to just build a shell and be a dick for a while, but I do want to say I am genuinely sorry you have to deal with that. Always being the victim or always putting on a mask is fucking exhausting and soul draining.

I recommend reading The Gift of Fear by Gavin de Becker. It's available for free at archive.org. It describes how predators work and how regular people can stay safe from them.

Give a couple examples of what you're taking about

I really feel for you mate. Vulnerable people get targeted constantly and it's horrible... they can get in a cycle of never being able to not be vulnerable because they never get a chance to fully recover. The funny thing is that vulnerable people see people's true self around them.

The main thing is working on self esteem, having good boundaries comes when people have the self esteem to do them. Have you worked on the causes of your self esteem issues? Counselling can really help

Some people only understand consequences. You can avoid them but if forced to interact, it's good that it is understood that messing with you might come with a cost. There are subtle and socially acceptable ways to convey this message.