Suddenly Jewish?

My maternal grandmother died last year (not from covid) and after her death, a bunch of family secrets were aired. Among them: My grandmother was adopted

She was born in ‘34 to a higher ranking nazi man and a Jewish woman (no further info on them available, unfortunately) — at that time such a connection was strictly forbidden in Germany, but if the father’s rank was high enough, they’d ‘just’ disappear a resulting child into the countryside, to some peasants wanting to adopt. And that’s what happened to my grandmother

Further: my mother is my grandma’s only daughter. If I understand correctly, according to orthodox law(?), this would make me a matrilineal Jew, no matter what, correct? Even though I grew up atheist and there being no culturally Jewish influences in my family (German/Swiss)? (Culturally, I am, of course, not a Jew)

I tried googling cases like this and they seem to be fairly common but I feel conflicted: After the atrocities Germans (including some of my ancestors, now even with a higher-ranking person) inflicted on Jews the world over and the shoah, it doesn’t feel ‘neutral’ as before to not have a religion. Like, I feel like if I let this die, that I would’ve helped in a way? I’ve been intrigued from time to time by religions, but always find too many absurd downsides — but especially Judaism was always interesting to me. But I felt it would be… I don’t know… tactless(?) to look into it more because of my family history (as I understood it before this revelation), although I do understand that conversion to Judaism is open to anybody

Am I blowing this out of proportion? What could/should I do? There is a fairly large congregation in the city I live in now; should I talk to their rabbi? I’m low-key worried that they’ll laugh at me for even asking such strange questions