My prized flower of the year

This plant was given to me by Rhonda, my neighbour a couple of years back. I believe it belongs to the cactus family. It grew larger over the years, and I thought that was all to it. And since I haven't been particularly attentive to my plants for the past few weeks (bloggers may know why) and also the hot weather, I was so so pleasantly surprised to see this. Felt bad that I didn't see it budding. Dunno how long it can last though..