Previous publication of my supervisor and a post-doc is a lie
There are lots of ways to go about this.
Since your advisor is a co-author on the previous paper, this may be difficult, since they are invested in the existing paper and have some credibility at stake. Theoretically, they should be happy to retract/rewrite the older paper, but we are human.  You are probably correct that they feel guilty- everyone with their name on the paper is ultimately responsible for all of the content.
At the same time, this can make some things easier for you. Finding an error in previously published work opens some new avenues for publication. Now, instead of a simple sentence, you can issuing a comment or a correction on a previous paper - many journals will allow you to publish a correction or remark on their previous articles, particularly if you can demonstrate a major problem or flaw.
Critically, do not be a jerk about this process. Simply state that there has been an oversight or error in the work by XYZ. Do not speculate as to why it went wrong or how. Even with evidence that their results do not match their data, there could be numerous reasons for it.   Journals don't want to be told they did a bad job, neither does your advisor- but everyone would prefer you correct an error softly and with tact rather than letting someone else do it loudly and disruptively.
Edit:  I am not sure your evidence is legally obtained, nor am I fully confident from this post that the evidence is conclusive that they were fraudulent.  Until both of those conditions are met, I wouldn't recommend making accusations of data fabrication - publicly or privately.  You will have, in all likelihood, a legal battle - for which I am not a lawyer. But you can conclusively say, as another commenter mentioned: &quot;We were not able to reproduce the results.&quot;