All four stays are twisted. Getting this straightened out means bending all four again. Then you are going to apply some torque again by riding. What happens when one of the stays stops bending and starts breaking? I mean I'm no expert but it just doesn't seem worth the risk. The frame is done. Get a new one.
At the risk of missing the joke:
http://en.m.wikipedia.org/wiki/Metal_fatigue
All four stays are twisted. Getting this straightened out means bending all four again. Then you are going to apply some torque again by riding. What happens when one of the stays stops bending and starts breaking? I mean I'm no expert but it just doesn't seem worth the risk. The frame is done. Get a new one.