Mellie was done,she had hoped Fitz would've changed his mind and realized he loved her or at least he had,a long time ago, before they ruined her! That's all she could think she would have just had sex with Fitz when ever he wanted or at least let him touch wouldn't have looked elsewhere and they wouldn't be in this it was clear now that he clearly never loved her and he is now happy with Olivia by his side,God good he proposed to her when they were still married and then he came to her again with the papers and she was so disgusted by him, she couldn't even dare try to convince him to reconsider was just gonna go but then he started with what else are you gonna take form me, and she couldn't any more she blew up and finally expressed herself in a way he never saw her before, a new Mellie. All he remembered was "goodbye Fitz" and her walking out and him yelling to her to stop but she didn't.