I am very angry and want to press charges but yet it is my wife's brother any thoughts?
Goodness. I'm sorry to hear about that happening. It is a shame that something like that can be done to us by our own family. Of course, your decision needs to be made including your wife, but something needs to be done. Whether it is taking it to the law or sweeping it under the rug.
I have had something of the same sort happen to me in the past, and I look at it like this. We are all human and we all make mistakes. I would look at as much of the situation as possible and decide what would be best for the brother to learn from this mistake. If he is a young and immature guy, $700 does seem like a big chunk of money to a lot of us, but it could have been waaaay worse. If it seems like he can learn from the situation, talk with your wife about having him repay it and set some terms on it with him. If he doesn't comply with what ya'll lay out for him, then by all means go ahead and take it to the police. There is a statute of limitations that will give you that leeway of when you can file charges on him at a later date. Hopefully, he just made a stupid decision and will do the right thing. I am always in favor of someone learning the right way to be and rehabilitating. We all know the criminal justice system really doesn't fix too many problems, and at times it makes things worse for the person in the long run for a simple mistake after they have paid the price for what they did.
However, if he is someone that is habitually doing crap like this, in and out of jail, constantly on dope, and always has no regard for anything but himself or what benefits him, you should go ahead and file the charges. It is not your or your wife's responsibility to take care of her brother, and it is not right for him to cost you money and put you into debt. Regardless of how pee'd off you are, the most important thing here is you and your wife. If you think that she will get over it pretty quick, make the call. If it might be something that she would not forgive you for, I'd let this one slide, but have some really strict guidlines on him when he is visiting. She needs to compromise with you as well and also needs to be aware of keeping your lives safe and free from that kind of worry as well.
I wish you luck with whatever you decide. Hope this puts some thought into the air for ya.