For many people, how they value themselves comes from other people.
This can be great when people are treating you well but when not so much when you’re treated poorly. You go from feeling good about yourself to not feeling good enough and because you’ve become reliant on other people to determine your value.
It may even get to the point where you almost feel lost and are unable to truly establish how you feel about yourself without it coming from other people. And so, you feel down and worthless whilst also blaming other people for how you feel.
I think that stage of blaming others continues until you’re able to realise that nobody else should be in control of how you feel about yourself. That’s not a solid foundation.