If the property was only in one brother's name, then he was the only owner. You didn't all sell the house. The brother who owned it sold it. If he gave you money after he sold the house, he made a gift to you. A gift is not taxable income to the recipient, and you do not show it on your tax return.
HOWEVER, the picture could change if your mother owned the house prior to her passing, and her will left the house to all of you. In that case, your brother mishandled the inheritance by putting the house in his name only. You need to consult a lawyer to straighten it out.
