Resign. Good game.
My one pawn advantage (files e-j) is not enough to do anything, and White's c-pawn in the meantime will inevitably promote. I probably played longer than necessary but the ending was fun, even though I lost. Final game position:
52.Gb4...Ke6
53.Gb5...resign
So the moves are:
52.Gb4 Ke6
53.Gb5?
Yeet