Sometimes you have to be pissed off first. Because we are hard learners, most of the time. At least I am.
For example: you build up a relationship with a colleague, co-worker, or client. You think it is based on mutual caring about the same thing, the same project, the same company. And because you believe we care together, for the same things.
And then you are confronted with the reality. That the people you believed in are in it for a different reason. Not for sharing and bringing, but only for taking.
Then you have one power left: end it.
Take your learning out of that experience. And approach the new situation as open as you can. With the learning of your former experience.
It will make you better. A better person.