You have my sympathy. Play "taps". Dig it up. Run it through a chipper or spend a lot of time chopping it up into small pieces and add to a compost pile.
The Cambium Layer has been destroyed. To keep it simple the Cambium Layer is just below the bark. Trees are nourished through the Cambium Layer. That is where water and nutrients are carried from the root system to the upper regions of your tree.
Are you sure your pest were ants and not termites? IDK what the "experts" say - termites DO attack living trees. I have seen it both in my yard and in client's properties.
How thick of a layer of petroleum jelly did you apply? First I would use Aqua Jelly instead f Petroleum Jelly. Apply a thin film more frequently instead of a thick layer. It does not take much to trap insects. A heavy application results in more harm than good.
Sorry for the loss of your tree. Try again.
Elizabeth - or Your Majesty
Living and growing in Lafayette, La.
When weeding, the best way to make sure you are removing a weed and not a valuable plant is to pull on it. If it comes out of the ground easily, it is a valuable plant. ~Author Unknown