Plum tree problem
Would appreciate some advice please.
I recently moved home and inherited a plum tree about 18 feet in height.. It bloomed well this year and lots of fruit appeared. Then the leaves went all shiny and sticky with lots of aphids underneath. The fruits started to wither & drop and I also noticed areas of black on the bark together with dark globules of sap. It seemed to affect other things in the garden so I took the radical step of cutting it to about head height leaving just three short branches above the trunk.
I imagine this wasn't the best course of action but due to the size of the tree, any spraying was out of the question. Will it be any good now if I keep the growth to a lower level or should I dispense with it altogether?
Any help much appreciated. Thank you