Yeah you will need to prune to a central leader. You'll need a good size post driven in beside it, a 10 foot t post will work well to support it. Then string it up to that firmly but not too tightly, just loose enough to not girdle the tree. It has just gotten too top heavy. If it continues after staking, you may even have to trim your leader back some. Dont worry a bit about cutting wood off right now, focus on roots and girth growth instead of limbs. I would actually go ahead and prune to get on top of the issue before you see many more flushes of growth. With the pruning you will release apical dominance and dormant buds will begin to pop so be prepared to see flushes of growth around the trunk, when you see them just hand pinch them off if you dont want a limb where it pops up.
If it stays like it is, you can pretty much guarantee it will split right down the middle in the future.