Why did my fig die (or nearly)?

[Shinpi]

We have had a struggling fig tree for the past 10 years, our lives have been really hectic until this year so we didn’t pay that much attention to the trees in our yard. However, as I am getting back into gardening - it seems our fig tree is nearly dead. It happened fast! I don’t have great pictures since it really happened so fast I didn’t think to document it. It looked ok and the next day all the leaves that were still on it was dead. The leaves started drooping (I watered more). Then we had some aphids so all the plants got the soap treatment. All looked ok but we only had maybe 5 figs on the tree, all of a sudden they started rotting on the tree. The leaves fell off and I watered it regularly hoping for some new growth. In this time, the tips of the small branches started turning black and shrivelling. I had to cut it down to nothing. I don’t want this to be a problem IF I can save the poor tree so if anyone has ideas on what it might be, I would be grateful to hear them.
Pictures are from before this. Maybe it helps 🤷‍♀️
It is planted outside, in South Africa and it is summer now so not time to drop leaves yet

 

[Shaft]

LLooks like it's been over watered heavily.

 

[Shinpi]

Thanks for your reply - we didn’t water any of our trees in the past. We have a relatively shallow water table so they get their water from there during the summer. I only started watering the fig tree when it started loosing its leaves.
We have now discovered an infestation of aphids and spider mites in the rest of the garden. It’s really frustrating because our potted plants are really healthy. The one day I was admiring a flower and literally the next day, most of the plant was dying. Our blueberries and raspberry I had to cut down severely as they were killing the branches as well.
My hypothesis at this stage is that the critters attacked the fig tree first because of its fragile stage and killed the branches along with the leaves before we could rescue it.
I watered the remainder of the tree yesterday and the little buggers were sitting on the bare trunks of the tree!
The root system wasn’t rotted and were still alive, just very sparse. It was planted by the previous owner in the worst type of soil and conditions so it never developed proper roots and got next to no nutrients.
Fingers crossed it comes back to life with some love and care