Freemasonry is most definitely
NOT a brotherhood of Catholics. Freemasonry has very anti-Catholic origins. In fact, the old European freemason lodges had as one of their goals the downfall of the Catholic Church.
An important question one should ask is why join an organization that is essentially anti-Catholic? Of course, if one is are anti-Catholic then this isn't much of a question. But if one
IS a Catholic, then freemasonry is a definite contradiction, and excommunication is the logical result.
Generally, willful freemasons are no longer Catholics. They are excommunicated.