If your skin was exposed in space and you bled would your blood be blue from lack of oxygen?

Presuming that, except for your arm, you were in a space suit and happily breathing, then your blood would still be red, as your blood gets oxygen from your lungs. As soon as the blood became exposed to space, the water and gases in your blood would instantly start to boil away, and whatever red-blood cells in your blood that gave it a red color would essentially explode. So, I doubt that there would be blood left to have a color (the above process is very fast).