I am sorry both for your bad news, but especially for the way you received it, the mistake that was made. Hopefully your Dr will check whose MRI he is looking at, before discussing it with the incorrect patient. When I have seen my MRIs my name is clearly visible.
I remember well the day my brother and I went to the reputable MS clinic at Oregon Health and Science University, we were told that we did not actually have MS. A relief. Instead we both had an adult onset of an unknown leukodystrophy, a fatal genetic problem. My MRIs do not have pinpoints of myelin damages characteristic of MS, instead there are large areas of damage, plus several areas of pure stroke damage.
Ironically, my father was a neurologist at the Mayo Clinic and was the world's leading expert on MS. When I was initilly Dx'd with MS, I read some of his publications which led me to the conclusion that the MS drugs makers were fudging their findings and could not be trusted, so I did not go on the MS drugs, and am thankful now for that decision.