
That’s just cruel. Just because you got hurt doesn’t mean she deserves to, too. She’ll still get hurt, but you’ll save her from it getting worse. Imagine if your friend knew you were getting fucked over or even cheated on and they didn’t tell you? This isn’t the answer, be better than these other people.
And also I might consider if your feeling for this friend are clouding your judgement here — is there some subconscious desire to be the shoulder she cries on when she realizes she’s been mistreated? Or do you subconsciously think she deserves to be hurt because she doesn’t return your feelings? If you ever want a chance with her you need to prove that you can actually look out for her. Or remove yourself from her life if you can’t be a good friend to her.