published Aug2016 , filing date Oct2013 and found public-knowledge Mar2013

[JkBnjmin]

Just wondering how a patent got awarded for this when is clearly public forum talking about the exact thing 6 months before his filing date.
And what does it mean now that the patent is awarded? Can he enforce rights to it on my manufacturing using the same process?
I never would have thought to have patented this process because to me its just obvious, and so obvious I was sure I would find people talking about it before his filing date when i discovered his patent finally, by accident really.

So what when he comes threatening me with this patent? Can he actually enforce this? Or can I just say, "Buddy, here is a forum on the internet talking in detail about this idea 6 months before your filing date, so, take me to court then buddy"?
How does it work?

[MYK]

A patent is considered valid and enforceable unless proven otherwise, so yes, he can try to enforce it against you.  You would have to invalidate the patent, either in court or in one of the administrative proceedings such as ex parte reexam, inter partes review, post grant review. . . .  If you want to do it on the cheap, you can consider building up a listing of prior art and then counter-threatening your competitor with that listing after he threatens to sue you.  It is arguably safer but more expensive to file an EPR/IPR/PGR with the USPTO so that you can have your say instead of relying on your competitor's common sense.

The description on the forum, if it can be properly dated, could be considered prior art.  You would be better off doing a patent search and finding patents and application publications dated before the filing date.

Yes, known stuff and sometimes even complete garbage slips through the system sometimes.  The various patent offices around the world can't possibly sort through every single forum posting ever just to invalidate someone's application.

Nota bene, if he files a lawsuit before you've filed for administrative review, courts often are NOT willing to delay the lawsuit while waiting for the administrative review process to complete.  You're more likely to get a stay with IPR than with EPR.