That thing is kind of a mess.
I'm not going to try to give directions on pruning, it would be hard to do. But pruning is about "seeing" where future growth should be, taking into account fruit position, opening up the branches to help with sunlight and to fend off moisture diseases, etc.
I would ask if someone from the local gardening club would like to pay you a visit. And do not be surprised if the initial prune is heavy. It will take a couple years to get it to where it should be. I also would not hesitate to plant this trees "replacement". Some new trees will start giving off fruit after just a few years. If the main tree is split, this may be something to consider.
Realize also, that fruit growers "thin" the fruit. If it were not for thinning, they would never get the quality of fruit they get, and the trees would be forever splitting on them.
Are you also fertilizing?