HI Ms Holling,
I am sorry you received that discouraging news, but I am glad that it was found before a serious event happened, and hopefully you can go forward with more aggressive treatments now that you know of the blocked carotid.
Have you met with a vascular surgeon to discuss options? After they review your complete history and current health, they may suggest some intervention on the blocked artery. If they do not, there are medications that can lessen the risk of strokes in future, and you should discuss this with your doctor.
Watching your blood sugars and keeping them well controlled, as well as your blood pressure, are the best approaches you can take on your own. Also be sure your cholesterol levels are kept under goal range. Definitely speak with your doctor about medications that may help decrease your chances of strokes with your carotid disease.
All the best to you, hang in there.