What is the difference between a real intention to divorce and an obsessive intention? Can obsessive-compulsive disorder obscure the intention or make one imagine it is a real intention? Is uttering a divorce pronouncement while feeling indifferent a manifestation of OCD?

Your divorce does not occur unless you utter it voluntarily, not overcome by your intellect. It appears that what you have mentioned stems from obsessive thoughts (waswas), and divorce does not occur by them. If you doubt whether you uttered the divorce due to obsessive thoughts or intentionally, disregard that doubt, as divorce does not occur by it, because the default is the continuation of the marriage. Therefore, turn away from these obsessive thoughts in their entirety, consult a psychiatrist, seek Allah's help, and frequently supplicate to Him to avert their evil from you.