It's gorgeous, if we help you save it, I demand a cuttling (I'm kidding, but it is wonderful looking!)
I googled Pereskia aculeata culture and the Purdue link noted :
"Flourishing with little or no care, the plant is drought-tolerant and suffers from over-watering. In greenhouse experiments, it has been found highly responsive to light. Under high light intensity, it can be kept erect and compact; under low light, it grows higher, with ascending stems and the leaves are larger and thinner."
So, although it is a tropical plant, I gotta think it's the water, too.
