She thought my breakup was a bluff?

"I'm a brunnette now, haha picture"

I chose not to block her from everything after I broke up with her, shortly after breaking up with her I cut contact, and we didn't talk for 7 days, she initiates conversation with that.

How do I respond to that?

EDIT:

Its an app where she can see when I'm online, you think she'll flip out when I don't respond and more so when I'm at her place picking up my shit?, also, can I just use her initiation to say when I will go? (still unsure when I can go get my stuff though, I havent told her). Theres a chance she will flip out and I will lose a chance to go pickup my shit. .

EDIT2: Cousin leaked she told her she misses me, but likes to be alone, and that she called herself stupid. This was yesterday, I was at her place , having drinks, I just responded "cool story bro".