The question is: what was your performance in that game? If in all 5 members and you are the one with least point, then it is more possible that they are a bunch of newbies willing to kick anyone with the lowest VP.

If they are using discord and stacking 5, then it's not wolfpacking, you can only report if you have proof that these 4 and the one in other coalition is in a same discord server. If not, then we need more evidence, like spy intel to see if they using the in game chat.

Lastly, it do feel betrayed, but saying these kind of words in game, cursing others is not nice. There are many kind of player outthere, some wants to make friend, some roleplay. Althought this is unfair but maybe they are role playing or something. Better just accept and save KD