So stupid of me

of (preposition)

9 a - used as a function word to indicate the object of an action denoted or implied by the preceding noun love of nature b - used as a function word to indicate the application of a verb cheats him of a dollar* or of an adjective *fond of candy
[M-W's Col. Dic.]

So stupid of me.

I think "of" is used in the sense 9b here but as the application of an adjective. Am I corrrect?

'I' is first-person singular subject and "me" is first-person singular object. Do I have it correct?

Please guide me.