This is the end.

[Adire]

What job was the healer?

If they were a scholar particularly, you shouldn't worry if they get a bit low. SCH has powerful burst MP regen and low heal costs unless they're having to spam Adlo or something. I'm regularly lazy with my MP management as a SCH because even when I'm lazy and let myself get low, I can build my MP back to to full very quickly. A low MP SCH is often deceitfully low, since Aetherflow gives 20% MP back instantly, is only a 60 second cooldown, can be reset by eating the fairy, and unused Aetherflow stacks should get spent on energy drain which restores chunks of even more MP. So to avoid wasting MP regeneration, SCH kind of has to let itself get a bit low and should be low enough for at least Aetherflow to fill it back up almost on its own if dpsing properly.

If the healer was a WHM/AST, you had more reason to get a little worried. Still, they should know when it's time to stop dpsing and save some MP for heals, and I have yet to have issues with MP when dpsing and healing, even as them.

Doesn't sound like the reaction you got was justified either way. I have low expectations of the community these days too. Can't blame you if you want to leave, I've been tempted to as well a few times.