SED was Marxist–Leninist and Die Linke isn't. In what universe are they the same party?
I don't believe they gave up Marxism-Leninism, they just gave the monster a new name and claim it is nothing like its predecessor. They do that a lot, changing the label on the package. Inside it is still the same monster, waiting to be unleashed.
If you want actual bona fide Marxist-Leninists, there's the cultists of MLPD.
And no, the few antisemites in Berlin Neukölln are not representatives for the entire federal party.