How can you get your girlfriend back if she moved in with you after two months and she said she was single but left you for her ex of five years?

You obviously were more committed to the relationship than she and it sounds like she used you until the ex was back in the picture. You should move on with your life and find a gal that is going to respect and love you unconditionally and not use you. If you "get" her back whats to say two years later she wont leave again. Then your heart would be broken even more. There are alot of deserving woman out there that will be willing to treat you well. Besides they had history together and you know what they say." History repeats itself" Good luck