My EX and I are sleeping, my feelings are blossoming? Opps?!?

You want the relationship because your ex-gf said you can't have it. If she had agreed to going back with you officially you would have wondered if it was really the right thing to do since it didn't work out the first time. We always want what we can't have. Enjoy your time with her but find a new and healthy relationship. Good luck! =)