You must say to your wife that you trust your brother and he can’t do this type of activity. He is very loyal to me and he respects you evenly. If she doesn’t agree then you should take your brother and your wife to face each other and then ask him had he has done this type of activity or not. If he says no then it will be assured that your wife is saying a big lie but for this you should have 100% trust in your brother.