There is a big difference between evidence that you have, or did, or created something and the protection provided by a patent. The only reason people apply for patents is to prevent other people from using their ideas without paying. People don't apply for patents to protect themselves from being sued by other patent holders.
I think it would be impossible for someone to sue you for breaching a subsequent patent if you have evidence that your method predated the patent. Publishing the method on the internet seems as good a way as any to get evidence. Maybe get a copy of the web page and a printed version that is witnessed and dated by a lawyer.
The other side of all this is that it should not be possible for someone to patent a method or product that is already public knowledge. In other words it should be impossible for someone else to patent your idea - except by accident. And if you had proof of precedence it may cause the patent to be nullified (if that's the right word) even if it had been applied for in good faith.
Where you do run a risk (and I doubt if there is any answer to it) is in not describing your method or product sufficiently to distinguish it from a later patent. As I understand it a lot of patent litigation is about very fine print.
On the other hand if the specific item you are using clearly pre-dates the patent application it is hard to see how the patent holder could complain. However it would be different if you make a version of your thing after the application date.
By the way I am not a lawyer and these comments are not worth the paper they are written on. If your doubts are worth it then get professional legal advice.
...R