Why is she being so stupid, and how do i win her back? i need answers asap because im meeting her tomorrow?

right, my ex and i have been split up for roughly 4 months now. we started being friends again about a month ago. last saturday i was sitting on a bench near her house, minding my own business, when next thing i know she comes along walking her dog. we chatted for a bit, then she asked me to come back to her place for a while. i went back, she put her dog in and we went to watch some tv. while watching tv, we were flirting, messing, tickling, cuddling, and at one stage she fell asleep on me while we were both lying on the sofa. when she woke up, it got to the stage where we started kissing each others neck, biting each others ears, stuff like that. then she said to stop, and wait till her mum was home so we could go up to her room. her mum arrived home and we lay down on her bed and started a film. i was in the middle of her and her bedside table, which her phone was on. her phone went off and she jumped on top of me to get it, so i started kissing her neck again. when she was finished on the phone she pushed me away from her neck and started kissing me. one thing lead to another and we ended up having sex. i love her so much, and we've been texting non stop since then. she says she doesnt want a relationship, so how can i get her to see that shes meant to be with me. before we broke up we were going out for 2 years. please i really need help i love her so much and im meeting her tomorrow. what will i say?