Care for Mary
25 Now there stood by the cross of Jesus His mother, and his mother's sister, Mary the wife of Clopas, and Mary Magdalene. 26 When Jesus therefore saw his mother, and the disciple whom He loved standing by, He said to His mother, "Woman, behold your son!" 27 Then He said to the disciple, "Behold, your mother!" And from that hour that disciple took her to his own home.
19:25-27 We see here several important truths concerning Christ's mother. (1) In calling Mary "woman" (v.26), Jesus is using a term of dignity and affection. Contrary to certain modern usages, this is a sacred title in Scripture, and address conveying deep respect and distinction. (2) In saying to John, "Behold, your mother!" (v.27) our Lord symbolically establishes Mary's role as mother of all faithful disciples in every generation. (3) If Mary had other children, Jesus would not have placed her in the care of John, for her own children would have cared for her. Thus the apostolic teaching that Mary remained ever-virgin is confirmed by His action. (4) Christ also demonstrates we must "even to our last breath show every care for our parents." John Chrysostom
(Also it proves Joseph was older and previously married with children from the first marriage, as Jesus's half brothers and sisters were older than he was in bodily form.)