I got mad....company found my unsigned contract after 1yrs (suddenly ha ha)...?

when I got this job I was told I'll work as self-employed....that's not an issue for me as I have another 3 freelance jobs...I was told I'll get an contract but I didn't I wasn't bother as I was thinking to leave anyway as they don't pay well I can get better jobs offers (and don't work another 3jobs) but now (I think they're scared I'll leave) they found my unsigned contract and in the contact is "any external web design/brochure work done will receive 50% of the fee"" ha ha...what shall I do..just slam the doors and leave or tell them politely I won't sign and discuss a contract??? I have to think about my references