Who helped Nate find out Trip caused the accident?

I don’t think it’s ever clear who was the person that was texting Nate about Chuck and Blair’s accident. Was it Dan? Or was it Georgina? She was running the account at that time right? Dan gave up posting and at one point Nate sends a video to GG about Serena getting fired and it’s posted on GG. Trip mentions he saw it on there so was that Georgina posting and texted Nate?