A few months ago I bought a little cactus and a jade plant at for my dorm room. I've been keeping them on an east-facing windowsill where they receive plenty of light, and I rarely water either for fear of root rot. A week or two ago my jade plant became rather limp and "floppy", so I watered both plants before leaving for Thanksgiving.

When I returned to my room at the end of the weekend, I was thrilled to discover not only that the jade plant had perked up but that a bud on the cactus had begun to open into a little yellow flower. Now, only two days later, the cactus has suddenly begun to collapse. Half the plant has "wrinkled" up and the whole plant has become floppy and unstable. Is there any way to salvage this plant, or did I somehow manage to kill it?