I don't remember the title to this book. Could you help me?

I read this book a couple of years ago and liked it a lot. It was the first installment of a series. The next book had not come out yet then. Now it is out, and maybe even the next book. It is driving me nuts that I cannot remember what it is called! It was a comedy about this girl in High School who accidentally drops her acne stuff down the shower drain and it opens up a demon portal (I know, it sounds really cheesy, but it surprisingly is a good book). This good demon guy comes out of the drain and then its just about how him and she get along (he enrolls in her High School btw). I remember the books title was about two words and I know that one of the words was Envy. The book was easy to read and was only about 200 pages or less. If you have any idea what this book is called, please tell me!