I've been watching the replay, here's the analysis:
In the first corner of the final lap, Furi gets a massive run on everyone and moves to the inside, touching akmuq, and takes the lead (for the record, I didn't push Furi). Then, in the next corner, I got to the inside and braked early enough, but akmuq came blowing by with a divebomb, which gave him a brief lead and left me in 2nd by some miracle. Furi then passed us both while I took a bump from Kartman (who was bumped by RPH), which causes me to touch wheels with akmuq, who spins, resulting in the "Big One".
Overall, I don't know who is to blame for the Big One, but I can definitely say that I can't find any reason to blame myself.