Her Child was dying for all mankind on the Cross. There is no mention in the Bible of her having any other children. Church teaching has always held that she had no other children. The preeminent Protestant Reformers all agreed that she had no other children. Brother of Jesus DOES NOT mean son of Mary, if you believe otherwise that is your prerogative, but it doesn't mean you are correct.
Jesus was her firstborn Son according to Matthew and Luke. James, Joseph, Jude, and Simon were His brothers according to the Gospels. James was his brother according to Paul. Jude was James' brother according to Jude.
The "preeminent Protestant Reformers" were wrong on this one and were influenced by their former Catholicism. The Bible mentions no other wives for Joseph. The Bible doesn't mention that Joseph had children by any other wives. Jesus's brothers and sisters travelled with Mary. They were her children. She was with his brothers in the upper room. She was with his brothers and sisters when they went to look for him. She knew not Joseph until Jesus was born, but then they were a normal married couple enjoying what God has ordained as holy in the context of marriage.
Sorry. But we will not make Mary into being anything more that Scripture portrays her as and I don't care what "the Church" said. Where the Church contradicts Scripture (and you really really have to twist and turn to make this into anything other than a contradiction) rejection of the Church's saying must be in order.
Of course, we know she is the first to whom He appeared, but trying to explain that would be like trying to teach Latin to my dead dog