18' birch in big trouble.?

I just planted a large whitespire birch 3 days ago in a new garden made up of existing sandy foundation below and 4" of triple mix above. Since then, we had mive amounts of rain and fierce winds that practically pushed this enormously heavy tree to a 45 degree angle. After a lot of work we have managed to "right" the tree again but discovered that the ground is like a mud pie from the rain. The tree is essentially like a ball in a primed socket. The leaves have started to wilt. Any advice on how to save this beautiful birch?? It's far too large to stake, and far to heavy to take out of the ground without istance from a crane, so re-planting isn't an option. Help!!!