My advice would be to turn that energy behind the fear to prevention. For example, now might be the best time to quit smoking, to lower the blood cholesterol, to make sure the blood pressure is at the right level. Second, remember that depression can be treated, perhaps easiest with one of the highly effective medications available, one of which can usually be found to fit the needs of the stroke patient. Finally, time can heal for the stroke patient as it can for all of us. Brain function improves, and that helps allay the fear or the depression.
Mobility improves, and that helps.
Our nine year old had a stroke with no known cause. Fortunately, stroke in children is quite uncommon compared to older adults. Unfortunately, the flip side is that because stroke is so common in general, children do not escape. Far and away, the largest category of strokes among children are strokes from unknown cause. It is often unsettling to parents and to the child when the cause is not found, and no doubt this has been the case for you.