Singer has accused pop producer of 'mental manipulation, emotional abuse and sexual assault'
Rapper calls on Dr Luke and Sony to 'let her do her thing'
The singer joined Zedd on stage for a rendition of the DJ/producer's hit 'True Colors'.
Kurt Vile, Kacey Musgraves, Emmylou Harris and others also set to perform
Singer recently sought release from ties with Dr Luke, who she has accused of sexual assault
Court has rejected Kesha's effort to break from her contract with Sony
The judge in Kesha’s case has ruled in Sony’s favour
Singer claims she rejected a 'freedom' offer that required her to say she wasn't raped
'I got offered my freedom if I were to lie' - Kesha
The popstar told fans that she has been working on new material<br />