Can I keep my wife from taking anything from the house while we are still married?

Until you have a court order, everything belongs to both of you and each of you is free to use it. A court can require a person who removes an asset to return it. If the two of you are separating, the right thing to do is to file with the court and get temporary orders, including a temporary parenting plan, in place. You can't stop an impending separation/divorce, so sitting down and having a rational conversation would be a good first step. Keep in mind that controlling behavior on your part will only hurt you in the long run. Everything belongs to both of you and each of you has the same rights before the law.