I know that people really do this to other people, I wrote it this way on purpose. connect the dots with me.
we learn to put ourselves down like this as a reaction to someone with power over us (parent, peer with social capital, etc) routinely punishing us for some way we are "wrong", often in confusing and contradictory ways, and forcing us to placate them afterwards.
when the person dictating the rules is irrational, the only thing we can rely on is that we've done something wrong, and so all we can really do to try to avoid being punished is demonstrate our willingness to be wrong. often, this isn't enough, and we respond by demonstrating it harder because it's all we know how to do.
the people who did it to you had some version of it done to them, that's why they treated you like that. if you're willing to treat yourself like this, you risk treating other people like that, even if only in your worst moments.
nobody should be treated like that, even if it's you and at your own hand entirely inside your own mind.
I know it's not your fault, you didn't ask to be this way, but you have to be better than them. I'm not mad at you for apologizing, it's not like it makes you a bad person. you'll learn how to do it less with time and care, you have good reasons for finding it hard to trust that people won't hurt you.
I'm not asking you to succeed immediately, just asking you to try. practice, make mistakes, get better over time. it'll be okay.