stop chewing the inside of my mouth

Ok, so this has got to stop! Last night, I sat reading a book and chewing the insides of my mouth like crazy. I woke up this morning and my lip was so swollen I couldn’t even go to my classes at the university. I look like I’ve been punched in the face! My fiance just keeps saying “just stop doing it” but he doesn’t understand that it’s some sort of weird habit. I do it while I’m watching TV, listening to a lecture, reading, anything…I do it without even realizing it. This is so ridiculous.