"
I may cry ruining my makeup
Wash away all the things you’ve taken
And I don’t care if I don’t look pretty
"I may cry ruining my makeup" - this means that someone has done something and she is in a lot of pain from that moment.
"Wash away all the thing you've taken" - refers to wiping the slate clean, moving on from that moment
"And I don't care if I don't look pretty" - She is saying she doesn't care about the pain she has felt and the way it has changed her, she will not let the change define her as a person.