Well driving home on the highway in pouring rain with a friend, I was driving 60 mph or so. All of a sudden I hear this deep engine sound. I'm like oh great, I'm far from home & my car sounds like crap. So I get off at the next possible exit, and park in a Toys'r us parking lot to look at the engine. I saw the wire to my exhaust manifold o2 sensor singed and hanging. It was dark so I couldnt survey up close in the rain, but I felt a study stream of exhaust fumes coming right where the exhaust manifold meets the front exhaust pipe. In my head I was like "I hope to God by exhaust manifold isn't cracked." So i tucked in the wire and sucked it up for my V12 sounding Camry.

Well I finally got the car home and took off the heat shield & felt around where the O2 sensor should be on the manifold... it wasnt there.

I was like WTF?!

I just kept feeling around and it just wasnt there. Well I unscrewed the bracket for the O2 sensor and felt around some more, NOTHING. & no CELs at all. So tomorrow I'll jack up the car and remove the front exhaust to make sure the O2 sensor wont be rolling around my exhaust if it fell in that way, which I doubt. So any explanation guys? What should I be purchasing for a replacement?
Thanks!