Making sweet from a fruit

The name of this fruit is frapa. It is like grapefruit but it is not grapefruit.
The tree frapa is in my garden. Every year, grandma was making for us a sweet from frapa. In Greece they make sweets from orange, lemon, strawberry, nuts, watermelon etc. All these sweets are made only with the fruit, sugar and water.
Now, grandma is in the hospital. Doctors say that the end is very close.
So, I decided to make the sweet myself, for the first time. I think I was successful. But grandma will not taste it...