If you go to the Spotify website, in the top right is your username. If you click on that, it will bring you to your accounts page. If you scroll to bottom of that page there is a buttun that reads "Sign Out Everywhere". If you click that it should log you out of all devices connected to your account. After that I would suggest changing your password through Facebook!
Hope this helps!
If I helped, please mark the response as a solution. Not a Spotify employee.