I know basically the bare basics of what's said to have happened about the crucifixion and I don't know how much of it is religious claims and how much is founded in historical truth in general. I tried looking for information on this by myself, but all the information I could find is what various religions had to say about it.
Unfortunately, there is very little information that can be known about the historical Mary, except that she was Jesus' mother and that she had a number of children besides Jesus (see Mark 3:31-35), including James "the Just." The last reference we have to her in the New Testament comes in Acts, which scholars date roughly to around the year 85 C.E. (along with the preceding Gospel of Luke). Acts 1:13-14 describes "Mary the mother of Jesus, and [with] his brothers" being among those gathered in Jerusalem with the Twelve (minus Judas) following the death of Jesus, and Luke may also suggest that she was present at the event of Pentecost shortly thereafter.
After that, sadly, Mary vanishes from the historical record. Naturally, Christians in later centuries wondered what had become of her, especially as Mariology began to mature within Christian theology during the mid-2nd century. It is during this time that the tradition emerges of her ending her days in Ephesus with John the Son of Zebedee, one of Jesus' disciples, but this is a later, apocryphal tradition, and so cannot be taken as necessarily true. Ultimately, as with so much regarding the early Christian church, scholars simply don't have the number of sources one would like to have, and thus, there is little that can be said about what happened to Mary after Jesus' death, except that she (according to the author of Luke) remained with the Twelve disciples in Jerusalem for some time afterward.
An apocriphal source (early to mid 2nd century) about the life of Mary is the Protoevangelium of James. It details Mary's childhood, marriage to Joseph, up until the birth of Jesus. It promotes the idea of perpetual virginity of Mary. The answer to the question "did Mary have other children" may vary accordingly on how interpret and read the Gospels. For example the Greek word "Adelphoi" was most of the time used for biologicsl brother. But Semitic people actually used brother for any closely related person of similar age (be it half brother, cousin, etc). Moreover because in the Gospel of John, Mary is given in the care of John, son of Zebedee, some might conclude that she didn't have other children to take care of her (why wasn't she given in the care of James the Just)?
A lot of legends and traditions came in the late 2nd up to the 5th century. The monasteries at Mount Athos claim a relation to Mary, but I don't know exactly from what texts they get their traditions.