Is it tacky to announce the end of your marriage through social media for those who did not know?

Is that stupid? My cousin former hubbye did that in order for people to stopped speculating or wondering about photos he had posted himself on social media with some other woman (The most stupid thing he can do, posting photos of him with a new chick on social media when many people he knew still believe he was married and did not know about he was no longer my cousin husband).

My cousin ex husband wrote one month ago like a poem on social media announcing it has been one year he and my cousin did not have a relationship. he caught many of us by surprise as we did not know they were no longer a couple that long, they camouflage it very well, beacuse he continue to attend from time to time family gatherings when he was no longer in a relationship with my cousin

So in that poem announcement the dude said he was writing that so people or family he had in common with his ex stopped wondering about the photos he had been posting on social media of him and another woman, and said that he already made a new life.

Updates
7 mo
He posted and mention about the break up over Facebook.
Is it tacky to announce the end of your marriage through social media for those who did not know?
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