Radiator fluid and my transmission fluid have mixed?

It appears that my radiator fluid and my transmission fluid have mixed. They are both the same light, milky, redish brown color. I noticed my engine pinging a little last week, (bad gas) and a small leak under the front of my car. At first I thought is was air conditioning condensation, but it took a day to "dry up" and it left not an oily residue but kind of like when something salty dries up.A white residue around the spot. Saturday the transmission started to shift hard and when we came out of the store there was a huge puddle of this milky fluid under the front of the car. I thought there was some protection between the radiator and the transmission to keep this from happening. I now wonder if I have ruined my transmission and my engine.