Identification: Need help

I have had this cactus for years, got it as a gift years ago (It was in a small pot, and had a pink "flower" on it The flower fell off years ago, and it has pretty much sat dormant. All of a sudden it has taken on a mind of its own, and grown out, up and crazy. I need to know what type it is so I can take care of it. I have no idea what all this new growth is or what to do with it.
Any help would be wonderful!

 

I think it may be a Pitaya or Dragon Fruit (Hylocereus undatus) or a variety there of.

 

I agree with Chungii V, the pink "flower" was probably another cactus, a chlorophyll-free Gymnocalycium grafted on top of the Hylocereus.

 

Thanks so much, I will research that..