I wouldn't do anything with her.. simply because she obviously wants something more then you do.. and that's really why girls become clingy (usually that is) YAY that you are a guy who notices that.. most guys I know don't.. and do stupid shit and get a stalker.. or someone whose coming on too strong
Just think of this... what if the condom broke.. and she comes back and says shes pregnant.. and you end up on the Maury show with ten guys all there for a paternity test with crazy. And if she's that crazy, do you want to put your penis in her mouth? But then again, the crazies are usually really good in bed. So how hot is she?.... just kidding. Don't do it.