Took iphone 3G apart. Headphone jack will not come away from antenna

[aor456]

Hi I need help please. I have taken apart an old 3G to see if I can replace the back housing. Everything has gone well apart from that I cannot get the screw out by the headphone jack as there is a nut sort of thing behind holding the screw in. I have twisted it with tweezers but its not budging. So I have all the top left corner and antenna strip attached to the silver frame. Any ideas how to separate them? Maybe i need another tool to get this nut off? Thanks