Johnny let me say first how sorry I am for your situation. Now on to the adaptation, you Can learn to shoot opposite shoulder, it is easier if you are not fighting left eye and right eye. You are going to be fighting a lifetime of muscle memory, especially if your shooting off hand, just go with the flow and DO it, it will come in time, if it is important to you, every time you shoot, let that thought get in your head, ( I want and need to do this ) We do weak hand drills all the time, and the environment dictates that what is done on this day. I don't like it, but do it, and it is good for me to practice or compete this way, I might just wind up like you, and due to training will not come up empty. Take the skills you already know, and apply them to the other side, don't give up, and work with it, I don't think it will come easy, but it will come with practice and a good attitude.
Best of luck, and never fail to ask for more info. I will try as best I can, as well as others here.