@dawson-mcwatch , one thing at a time. Your Diplopia (Double vision) is caused by a convergence problem with the line of sight of each eye. This is potentially fixable.
An Orthoptist can measure the degree (angle) of the problem and supply a prism, which can be added to one lens on a pair of glasses. This will divert the angle of the line of sight on one eye for a successful convergence.
By periodically reducing the strength of the prisms, the brain can be trained to correct this problem.
Then you can see if you can build up your muscles/stamina. But, do it gradually.