Go back to the pawn shop, explain, do a deal, and redeem it, they can only sell it after a specific length of time depending on the value of the goods and the money lent. The sooner you get it back, the less interest you will pay. If you are skint, then your phone is going to be the least of your problems. If necessary, get the sim card back, and borrow an old phone.

Ditch "the other half", unless you are junkies together. In that case, again, the phone is the least of your problems.