Well, since you're obviously not home, I don't think keeping your tail is much of a needed secret. That is, if nobody you know is here. It's not something embarrassing right?
First of all, you are indeed on Earth, if that's where you're from, but just a different one? It's hard to explain because a lot of people that have appeared here suddenly are also from Earth, just from another... dimension? Sorry, I'm not really used to that terminology quite right, but I guess that's what it's called. Unfortunately nobody has figured their way back, even those with all sorts of magic. I also will apologize if any people in town might give you a rough time at first. It's not as bad as it used to be, but still.