I'm shut up

Dear Tdol from your answer to blacknomi about "I'm shut up"

blacknomi

I am shutting up. ( doesn't make sense, "shut" is a verb that usually doesn't use continuois tense)

1.Does your "I'm shut up" mean "I'm going to shut up"?

2.Does "I'm going to shut up" is the same as "I'm shutting up"?

3.Doesn't "I'm shutting up" follow the normal rules of grammar, I thought that we can use present continuous tense when something's gonna happen in the near future?

[Tdol]

1 I'm shut up = I've shut up.
2 No, the first is future, the second is present.
3 We can, but it's for fixed things in the future like appointments, so it doesn't really work with 'shuttin up'.