How do you set firm boundaries? They seem to keep doing whatever they want to take into account how it affects me.

True, narcissists don’t care how it affects you, so I would let go of that expectation and enforce consequences for not respecting my boundaries. Try to only enforce 2-3 boundaries at a time and be sure you are clear on communication, to the point, nothing extra. You MUST enforce the consequences or none of your boundaries will be taken seriously. It’s going to be hard at first because they are use to getting away with it, so hold strong. Think about what their reactions will be and how you will handle it with no emotional charge, not allowing them to run you in circled conversations defending yourself. You have the right to set healthy boundaries for yourself.