Another thing strikes me, OP, when you talk about switching off feelings.
I don’t switch off my feelings, but I make pragmatic decisions about how to protect myself and respond with dignity, and I strenuously resist the urge to ruminate or stew. This takes work!!
Some of this is stuff I learned over the years about emotional regulation and boundaries.
Some of it is just the dumb luck of biology and neurology, as I have never had difficulty with impulse control, and my emotional struggles are more in the arena of low level irritability than being flooded all the time by big feelings. I think people who experience a lot of mood instability do have a genuinely much harder time with pulling back and making considered decisions in relationships - and tend to skew more anxious than avoidant.
But basically I remind myself when I am hurt that I can’t control other people’s feelings or behaviour. So if someone has demonstrated beyond reasonable doubt that they are volatile, or unreliable, or simply that they don’t like me very much, the smartest thing to do is withdraw any emotional investment in them, so that I’m not throwing good energy after bad.
If someone is giving me the impression they’re not interested in me, I take the hint. I respect their right not to like me. I don’t like everyone either - even if they’re good people who’ve done nothing wrong.
I don’t try to work out what I can do to make someone like me if they don’t. I make sure to behave ethically, so I can be sure I haven’t deliberately fucked anyone over, and beyond that I let people have whatever feelings and opinions they have.
It hurts if someone I like doesn’t like me, but that’s life.
Another thing about switching emotions off - people have different nervous system responses under stress. If I find someone difficult to be around, I dissociate. Without consciously choosing to, I retreat inside myself and emotionally play dead. I’m perfectly calm and polite, and can keep a conversation going pleasantly enough but I’m not really there. They can’t hurt or irritate me too much, as my real self has left the building and I am giving them a perfunctory performance of whatever social niceties they want to extract from me.
This is an automatic coping mechanism I have - and I am glad to have it as it’s generally served me well. But other people’s nervous systems might put them into fight or flight instead, which is harder to manage.
I do think a lot of this stuff is the luck of the draw biologically as much as a response to attachment and relational trauma.