I need advice from woman?

To me it sounds like she's had time to think and she's decided that she doesn't want to get back together with you. If she's started to act cold/selfish lately than that probably means she want you to leave her alone and allow her to get over you. Of course I could be wrong, I don't know the situation or the parties involved so I could be completely wrong but that's my view of it from the description. Good luck!