The person with 250k subscribers is obviously more experienced with YouTube. Why don't you learn from this guy, find out how he is getting subscribers and creating a solid audience. This way you will know how to increase the number of your subscribers and have a stronger channel of loyal audience so people can't push you around like that?
Change your mindset. Calm yourself and forget about revenging for now. Steal his tactics, become a better YouTuber, and f*** him up later with a snap of a finger. Heck you probably wont even give a damn about him when you are at that level.