Glad Bughead worked it all out in the end, but I think Jughead overreacted here. I understand that he has some unresolved issues with birthdays, and Betty's surprise party triggered an angry reaction. After all, his whole issue with birthdays stemmed from the fact that his dysfunctional family always played fake nice for that one day. So, when people (including Kevin and Veronica) were there even though they never would have come over/been his friends in general if it weren't for Betty, he may have felt like it was reminiscent of yet another birthday where everyone was fake nice to him.
It was one thing to be angry about the party and to emphasize that he is an outsider. But, I don't see why he put so much blame on Betty. Archie was the one who told Betty about his birthday, invited everyone to his house, and told Cheryl and co. to come right on in. Betty didn't know the full extent of his birthday issues, and she didn't intend for this to get out of hand.
Betty also did really nice things, like go to the movie with Jughead, wear the crown top, make him a burger cake, etc. I thought it was unnecessarily rude of Jughead to then turn that kindness against her and say that she was just trying to benefit herself, fulfill the good girlfriend role, take him on as a project, etc. Although I did find that part of the fight to be realistic and interesting, I guess I was surprised that he went there at this moment--when Betty really didn't do anything wrong or over-the-top by making him a cake and inviting a few people over. Plus, he knew that she was having major issues with her own family, so who is to say that she didn't want to plan a small party so that she could find some relief from all that and share a moment of enjoyment with her friends?
But, hey, he's an introverted teenager and he was angry, and they made up, so it's all good.