Is it a "true split"? I.e. are both sides broken away, or is
only one side leaning away from the separation? If the second
case is true, you could possibly just remove the broken away
side. You'd have a nasty wound, but it would likely heal over
in time just fine. In the short term you'd probably want to
support via staking or other method in the area of the wound
for a few years.
This is just an opinion, so if someone disagrees with this
thought, definitely voice your reservations.