I saw a post that was really wrong and misunderstood some aspects of the movie that I think are very common among musical fans, because they are still watching it through the context of the musical, and are unable to divorce the two stories - even though they very different - so all their conclusions are filtered by that.
a) Veronica never "bullies" or "abandons" Betty Finn (as far as we know), but Veronica is still a bully, who has become repentant just prior to the beginning of the movie. But we don't know for that sure, of course. We do know that she didn't go to Betty's birthday party, which is rude, and we do know that they stopped being friends and Veronica doesn't really associate with her much (she had to convince Heather to let her talk to Betty, who was visibly annoyed with her the whole time). But we know she does participate in bullying other kids (like she did with Martha), and that she "used to have a sense of humor" about it. This is to say: While it doesn't show her outright bullying Betty Finn, there is no reason to assume Veronica has never bullied Betty Finn. This is sort of a non-point, but it will be important again when talking about Heather Chandler.
b) In the movie, it is implied that Heather McNamara knows she is not being fully forthcoming about the double date with Kurt and Ram.
The cut away shot is so we know we immediately know that was Heather McNamara had promised her is not going to be true. And of course she knew that: Kurt and Ram only see the girls as sex objects, and their literal first lines are about how much they'd like to fuck Veronica (and Heather Chandler), so obviously, them wanting to bring Veronica along can only mean one thing, despite what Heather McNamara assures her. It's a mirror to the scenario at the Remington Party with Heather Chandler in many ways: Heather McNamara is doing this because it's what expected, and she expects Veronica to go along with it, too. Just like how Heather Chandler expects her to sleep with Brad, even when Veronica doesn't want to.
(Also, the almost rape scenes are so different - both in set up and resolution - that they are hardly worth comparing, beyond pointing out they are different. The characters have deviated so much from the original intent of that scene that is no longer the same scene, and those are no longer really the same characters.)
c) Heather Chandler does not think she is helping Veronica at any point. I think this is the most Musical (TM) opinion shown, but the fact is that, in the movie, Veronica does not have a Nerdy to Hot transformation, and she is never implied to have done it. All we know is that she wanted to be friends with the Heathers at some unidentified point prior to the movie, and while there isn't any reason to assume she could never have had that Nerdy to Hot transformation, there's also no reason to assume that's what happened. She is a popular girl who is gaining self awareness about how people see her, but she is a popular girl. That is, in fact, the basic premise of the film, as it was originally concieved of: A sadistic popular girl kills her peers. It went through a lot of transformations to get to the final product, but what never changed is that Veronica is not meant to be a nerdy underdog in the movie, because it is a parody of 80s teen movies, where the main characters are always nerdy underdogs. Heather Chandler isn't helping Veronica and 'giving her life advice' or whatever; she is an equal, and not a protegee.
Now, I assume OP was also referring to this:
In which case: This is Heather's justification for how she treats everyone in school. This is her justifcation for how she treats Heather Duke, Martha Dunnstock, Betty Finn, Country Club Courtney, The Geek Squad, etc etc etc She does not actually believe she's helping anybody - it's just her excuse for mistreating people. She's basically saying, "Life's not fair"/"This is how things happen in the real world" to justify whatever inane bullshit she does to her peers. But she does not genuinely believe she is helping anybody, least of all, Veronica.
d) For some reason, OP thinks Heather Chandler only threatened to ruin Veronica's life in the musical?
They are the same lines. In fact, I think the musical abridged her tirade, because it references things that don't happen in it originally. And in the musical, Heather Chandler is not threatening to ruin her life because Veronica didn't want to have sex with a creepy college guy! I guess Heather puts hands on her in the musical. Perhaps that part is what's makes it worse.
e) Heather Duke is made worse in the musical in some aspects, since they also wanted to make Heather McNamara "The Nice One," but it's really just...not that different? I guess we expressly see that Heather Duke is the person going around telling people Veronica's a slut (which, by the way, is basically just a manifestation of what Heather Chandler threatened to do to her; and, in the movie, though we don't see it, we can assume Heather McNamara and Heather Duke are both doing it, because they are all mean girls). Actually, the thing about Heather Duke is, we're just supposed to realize she is acting like how Heather Chandler would be acting - so if you don't think Heather Chandler is acting that badly, but Heather Duke is... You have some weird biases.
And, in conclusion, I know they are worse friends and more irredeemable in the movie because they are never meant to be redeemed. Veronica doesn't remake the school's hierarchy to be a kinder, more gentler one - she realizes the fact that there is a hierarchy that people at the top can effect, but none on the bottom can, is bad, and "commits (social) suicide" by abandoning her old friends and befriending the "social Siberia" that is Martha Dunnstock. (And this is, of course, a grafted on ending, whereas in the original, Veronica would defeat JD, and as she's walking through the school with the detonator, realize her classmates weren't worth saving, and blow it up anyway. Which is...certainly a choice.)
In the musical, Veronica realizes that they can still change and things can be different, and that the people in her life are worth empathizing with and caring about. "The real love story is between her and the school," as the playwrights said. That's why the final song is the reprise of a love song? And they all hug and hold hands? The end of the musical is really the polar opposite: She is an outsider who joins the collective, rather than an insider who has become disillusioned by the abuses of society, and ultimately chooses to reject it entirely.
I'm not saying one is a better message than the other, because I don't care, but the musical gives every character a personality face lift (with the exception of Heather Duke) and makes everyone as 'good' as they can be in their circumstances (even when it makes the story...weird...in some parts). The musical is idealistic; the movie is pessimistic and cynical.
Anyway, a mild rant, but a lot of people seem to think this? And a lot of them are movie fans too, which is weird, since I prefer the cynicism of the movie to the saccharine characters of the musical. But I also see a lot of the points that people who can only parse the story through the musical make (namely, not realizing Veronica isn't a nerdy outsider ever, at any point, as far as the movie is concerned, or thinking since Heather McNamara is the "good" Heather, that she only ever has good intentions) . But the point is, "They are ALL mean girls." It is about how girls hurt each other. That is the plot of the entire movie. Get crucial, guys.
