Emotions are generally heightened in dreams, and occasionally bring a bad experience such as the one you described. It is possible that you were in between REM periods (as mentioned before) although this is quite rare, so it may be that you were in the very early stages of sleep, which may explain the spinning and falling sensations.

Most LDs are unlike this, and I'd suggest having at least one more before stopping altogether, although emotions can be quite powerful, and I'd understand if this experience deterred you from LDing.

Echoing the sentiment of the thread: It's your choice either way.