Removing Dye that Transferred in the Wash?

I washed a load of clothes all lights and darks. I usually never have to separate. But this dark pink shirt bled onto my pale light blue shirt and has left splotches on it. Luckily it didn't get dried. I called my mom and she said to soak it in vinegar water. I'm scared it's not going to work. Please help! It's a favorite shirt.