Dirty (Filthy Rich, #1)
Julles Burn

Now Lenore sells cars and fights for commission against Ericka, the new salesperson whose perfect figure seems like it’s winning her more than mere sales. And Zack’s too busy being popular to recognize the trouble his long-time crush has gotten into.
When both decide to investigate the secrets of Ericka’s success, they go about it in very different ways, and Lenore’s addictions threaten to consume her.
Note: This is Episode 1 of a serial. The story is gritty and realistic. Includes erotic scenes. For mature audiences only.