I'm pretty close to positive that it's not a Pedilanthus, but it's not obvious (to me) what it is. Something in the Kalanchoe / Bryophyllum area, maybe?

Whatever it is, it doesn't look to me like it's getting enough light. It may have other problems beyond that.

I have this plant, it's not a pedilanthus.Look up Kalanchoe daigremontiana or pinnata, it's one of those two. It forms plantlets in the leaf serations and we have to pull them out of the surrounding plants.They get leggy in winter with too little light. Just lop them in half and give them more light. There's a thread in the cactus forum talking about what an invasive weed it can be in the southwest.

I've got one, it's over 4'tall and flowers from Nov through April! Just give it as much natural light as you can in the winter and keep it cold and dry! Mine is in a southern window, temps get to upper 30s low 40s at night, and I water it maybe every 5 weeks or so over the winter if it's a warm day. It takes about 3 years to flower indoors, very pretty salmon colored bells. I'll try to get a photo later today.

I lopped off the tops. I left the bottom 4 or 5 sets of leaves. Did I do the wrong thing?

Nope, it'll be fine. Just be sure to give it a lot of light and don't over water. It will sprout new growth, you can root what you took off as well.
Expect little babies to form on the leaf margins as the plant gets more light.