Imagine a man who wears a special beketishe lekovod shabbos every week. He maintains it meticulously, and looks forward to honoring shabbos with it every Friday night. One day, his son tells him “ta, did you ever get that beketishe checked for shaatnez? It says wool on the label”.
To his horror, this hero of kovod shabbos somehow forgot to check. He had been wearing shaatnez for perhaps decades. His refilos, though he was shogeg, were not niskabel. He cries and mourns. But he moves on. He recognizes his place in the world and the awesomeness of Hashem, and that he can do teshuva no natter what. Hashem will forgive him even if he intentionally wore it, and certainly if it was accidental.
Realizations are difficult. It takes fortitude and the ability to stand humbly before the ribono shel olam and accept that we aren’t perfect – we make mistakes, whether due to inattention, miseducation, just not “chopping” or other issues. We try our best and know that Hashem knows our fallibility and weaknesses. He is yodeah yitzram, ki heim basar ve’dam.
To not be able to accept the imperfections in ourselves leads to sholom bayis disasters… often husbands reject culpability due to their unwillingness to accept that they were wrong, even though they know it deep down. People lose their businesses over not being mevater. Teachers lose students when they refuse to accept that they’ve erred. And ovdei Hashem like yourself, who shudder at the thought that they’ve been mistaken for decades can lose the chashivus of their avodah if they insist on being right – the choice is yours.
I am leaning towards thinking that it’s mutar in any case, but the emotions behind your thankfully honest reply are not befitting someone who cares deeply about shabbos and Hashem.