DO NOT under any circumstances plead guilty to a theft and pay a fine. You will regret it the rest of your life. A theft conviction will follow you all your life and could prevent you from getting an apartment, a good job, getting many types of professional licenses, etc., etc. You may not realize it now but this could very costly for you later on.
You must get a lawyer to review the case to make sure the state can prove you did it. If the evidence is strongly against you, there are other ways to prevent a final conviction. Deferred adjudication, special expense, pre-trial diversion; all of these may prevent a final conviction for a theft.
Do yourself a big favor and spend the money on a good lawyer. The court will appoint you an attorney if you cannot afford one. Better to spend money now and get a good criminal lawyer. Do not get a lawyer who only dabbles in criminal defense, get one who does it full time who can advise you better.
I agree. You will regret a decision to plead guilty. That can never be expunged off you record. Other options are a pre-trial diversion or a deferred probation. With either result, you can either get your record expunged or sealed. Good luck!
Theft is a crime of moral turpitude, and a conviction (or even a straight probation) for theft can have many negative consequences, including the inability to get a job (who would trust a thief?), the inability to get housing, enhanced punishment if you get in trouble again, and impeachment if you are in a lawsuit in the future.
You need to hire a lawyer who can help you get the best possible outcome. While it is not likely you will get a straight-up dismissal, it is possible that you can get a pre-trial diversion or, at the very least, a deferred adjudication probation.
Do NOT listen to your fiance's sister. A final conviction is NOT what you want because it will stay with you forever.