Split Tree Limb
Sorry, but there is not a chance you will be able to fix this. There is a lot of physical stress on that limb, and to get it fixed you would have to use lag bolts or threaded rods with large washers counter sunk through the bark to the wood. Then you would have to get it to close with that hardware -- I'm pretty sure you wouldn't be able to do that. If you did though, then it would have to stay stable and firm until the would had a chance to join and callus over, which would take many years. After all that it still wouldn't be very stable.
I'm afraid that what you need to do is cut that entire limb off, hoping it hasn't split into the trunk. The tree will adjust to the change in weight distribution. It also will start growing branches in that direction. You will be surprised how quickly it will fill in. I notice a couple of large flush cuts that are very harmful to the tree. You might want to look at our web page with tree care articles - http://forestry.usu.edu/htm/city-and-town/tree-care - and at a particular fact sheet we have on pruning at http://extension.usu.edu/files/publications/publication/nr_ff_004.pdf.