Tracy: He was crippled, but only his body was cracked. It's not simple, nor is it an easy matter to explain. "Let's just leave it at that," she says and closes the holy book of lies. She covers her eyes, denying to herself what she thought happened.
Tracy: Mom, I have to go to the bathroom now.
Melanie: Can't you hold it a minute?
Tracy: That's how you get a bladder infection, you child abuser.
Melanie: That's dramatic.
Tracy: Mothers, lock up your sons.
Tracy: Geez, Mom, why don't you open a hotel? You could get paid for all this shit.
Melanie: I want you here with me. You're my heart. I'll make it right.
Answer: Tracy acted like she had done everything Evie did before. She pretended she was already bad to become friends with them, so Evie thought she had found someone who was like her. Evie was definitely also in love with Tracy, but was also jealous since Tracy had a family who loved her. She wanted that. Yes she used Tracy, but she also cared about her.
I don't think Evie was romantically in love with Tracy. It was more about her wanting to *be* Tracy, with a mother like Tracy's. Also, she seemed to know that Tracy was only pretending to be "bad." I think Tracy's innocence made Evie sad, because there was a time when Evie was more like her.