Weird question, but I'm a little lost right now lol. My mom always told me her mom was raised Jewish and my mom's grandma was born Jewish. She's not at all religious and raised me atheist. I've done my best to keep kosher, study Torah, learn Hebrew, attend services or go to shul, perform mitzvot, etc in the past decade or so, and definitely thought of myself as a ba'al teshuvah.
Lately, I decided to get on a genealogy website and look into my actual ancestors. I found US census records, military draft cards, hospital death certificates, marriage licenses - extremely trustworthy, verifiable sources - going back to at least 1880 in a very clear trail. My grandma's extremely Polish maiden name came from her Polish Catholic father. Grandma's grandmother and grandfather came over from Bulgaria in the 1880s and were married in a church.
While it's cool to see my great great great grandparents' actual handwriting and know where they lived, I was completely wrong about everything I thought I knew about my family history and I feel like a complete berk. I genuinely thought I was Jewish. I wasn't trying to lie to people or misrepresent Judaism to curious gentiles or worm my way into Jewish spaces in order to proselytize. I still definitely want to continue my study and officially convert, and I'm trying to work up the courage to lay it all out in front of the local rabbi and ask what he thinks I should do. I've only gone to two Yom Kippur services and a few study sessions over Zoom, so I don't really know him or the congregation well.
I don't want to come off sounding like I intentionally lied to him or that I'm trying to get special treatment or skip steps during the conversion process. This is a genuinely jarring realization that's changed the way I think about myself and my faith. Do you have any advice for me going forward, or do you know someone who might?
To be honest, I'm... Probably not the best person to turn to on this topic. However, I can try and help.
You didn't lie to anyone, and this kind of things can happen. You can probably said you were told by your family you were Jewish but upon investigation you found out your great grandparents married in a church. Now, technically that doesn't directly point to the idea that your grandmother wasn't Jewish - she could've been a Jewish woman attempting to assimilate with general society, or have converted to Christianity (which according to Orthodox Judaism at least doesn't change her descendants' claim to Judaism.
Honestly, at this point... I think it's more a matter of having courage to talk to the Rabbi about it than it is about things of the religion. And yeah, gathering courage to talk to an authority figure you barely know is going to be hard.
I don't know if it'll be helpful, and I hope this won't hurt you, but I know a joke about people in a similar situation don't take it as me laughing at you for being where you are, but maybe it can help add levity to your eventual conversation with your congregation's rabbi. Anyway, here goes:
Three Jewish brothers found out that their mother wasn't Jewish. One was a Hareidi, Ultra Orthodox; another was more Neo-Orthodox, but tended to go with strict Halacha; and the third tended to go with more lenient Halacha. When they found out they are Goyim, the latter immediately went to eat pork before he converted - since, as he got some time to be Goy, he could at least enjoy it. The second, on the othr hand, went to eat meat from a cow that had a hole in her lungs, as up to today he went according to the Halacha that it is forbidden. The first said: "oh, now I can drink Coca Cola!"
(Hareidim tend to only trust very specific Kashrut brands. Maybe there could be a version with Orthodox, Conservative and Reform Jews, but I never heard one.)
If you still feel trepidation... you can, perhaps, turn to others on Tumblr that are better suited to that than I. I'm an Israeli Jew and I assume you are American, so there might be cultural differences. I suggest you try be open with your Rabbi, personally, but I might be missing something cultural that is different outside of Israel.
I wish you good luck in talking to your Rabbi and your conversion process!