Well, for starters, I'd remove that big vertical... if it's allowed to grow and crop it will put even more stress on the bent "leader". Looking at the base of the tree it is hard to see if the rootstock is what has developed into the tree or not. That double growth in the area of the graft point is trouble...creating bark inclusion and a weak joint that will eventually split. The main branch bark also looks like is , or has in the past, split just to the right of the support posts.The tree is most likely bent due to allowing a full crop on a weak, or undersized, leader. Unless the apples are a great heirloom variety, which can be grafted over onto a new root stock, I'd take the tree down and start over with a bareroot tree,or trees, from a reputable nursery supplier...one or more varieties you like. Be mindful of cross pollination requirements.
Poor tree, sadly neglected at best.