My take is he floated you OTF, hit his King and is afraid you have the FD. He is happy to take the pot down now and is trying to talk you out of calling - he might even have K
Q/J/T
which in that case we're doomed.
We certainly cannot rule out him having an 8 either.
Assuming you were 1st to act OTF, I do not like the massive bet. We're 5 handed, and it's asking for trouble.
I know we're afraid of giving a free card and seeing another
or an Ace hit the turn, but I think it's more likely than not that if you check, some one will find a reason to bet here. When they do, you can evaluate if you want to raise, or just call for pot control based on whether or not it will be HU OTT.
As played, fold.