No, you shouldn’t take a deal on this charge of joint possession. Instead, get the best lawyer you can and fight. Your lawyer can explain to you the idea of "common" areas and "private" areas. If the drugs were hidden in the kitchen for example and only one of your roomies has a history of possessing that particular drug, you could well be found not guilty. If it was found in the drug roommate’s individual room, then the police may just be dead wrong in even charging you, and a judge might dismiss your charges if the prosecutor won't. You don't even know yet whether the police exceeded the authority of the search warrant. Did you read it? Did it allow them to search one roomie's areas and the drugs were found in another guy's room? Whose names are on the lease means nothing.
Don’t take your legal advice from a cop any more than you’d get dental advice from a auto mechanic. Otherwise, if I dropped my meth during a White House tour, they’d arrest the President. You have to know the drugs are there to possess them. You sound like you would make a convincing witness. If all else failed, you stand a good chance of getting acquitted by a jury of 12 just on your word. Remember, you only need to convince one juror. The prosecutor has to convince all 12.
Don’t even consider folding until you get experienced legal advice.