Just ignore it. Use your original OG and whatever the eventual FG is. Doing the calculation may upset you.
For most beers, the addition of fruit actually lowers the effective OG. Fruit contains roughly 10% of sugars per lb when compared to plain sugar. Of course it does vary by fruit.
Assuming your fruit has 10% sugars, 10 lbs of fruit made up to 1 gallon would give a gravity of 1.046. 10 lbs is a large volume. Some fruits that have about 10% sugar (by weight) are apples, blueberries, blackberries, cherries, kiwi, pears, and plums.