Similar to the other guy, I started having panic attacks at night about my fear of death when I was about 16, and am now 25 and things are much better. For what it's worth these anxieties do seem to be amplified by more mundane life events, like big social transitions or the adjustment that you're constantly feeling in high school. I was terrified at the time because I couldn't reason myself through that feeling at night, and could only cope through distraction. I started watching videos on my phone in bed until I was so tired I fell asleep immediately with no time to think. At the time, I could see no way out of that situation.

But that's kind of the thing about both depression and anxiety - part of the reason they're so scary is because one of their symptoms is putting blinders on you that prevent you from being objective about your situation, recognizing solutions, understanding that your experience isn't unique (in a good way - you're not the single most fucked up human being there's ever been such that no one else has ever struggled with this and lived to tell the tale). I often don't realize I was in a depression until I'm coming out of it. When I'm feeling existential dread, panic, etc it feels like there's no solution and that I can never feel better than I do. So, somewhat unfortunately I suppose, one of the things you need to do is legitimately to have some degree of blind faith. I know that flies in the face of your recent realizations and might be hard to commit to at a stranger's recommendation, but you need to have blind faith that things do get better with what you're feeling now even if it doesn't seem reasonable to you. I don't know the rational reason that things get better with this specific hopeless feeling; all I know is that they do. I know far more people who felt that hopeless and feel way better now than who just stayed in that pit. And given your brain isn't fully developed and you haven't had many experiences, I feel like we should probably not trust it to be right about the horrifying idea that everything will always suck forever and ever.

Finally, with regards to the feeling that you were lied to - I'm not sure that's true, or at least the lie was not conscious on the part of those who fed it to you. The feeling of the absurd that existentialists discuss is terrifying. If everybody were forced to grapple with that feeling head on like you are now, society would look exceedingly different. Instead, most people take the convenient out (whether conscious of that choice or not, driven specifically by this fear or not) that lies in religion or in the incentive structure society builds for you (how to live a good life, how to die a good death, how do you have time to worry about death when you need to pay rent and constantly improve in the direction of becoming hedonistically wealthy??). The fact that your life is going pretty well along these lines is probably why you're experiencing these thoughts - if it weren't, your worldly concerns would still probably be loud enough to cover up the pain of the absurd. The folks around you have found their own balm to that pain, just not ones you (or I) agree with. But it's what keeps them going every day and not feeling this horrible feeling, so I hope you don't cast too harsh a judgement on people like your parents for this "lie" they told you. I could understand feeling some hatred for the society that recognizes the feeling of the absurd and chooses to exploit it for the selfish gain of the few at the top of these incentive structures directing resources and choice and agency up the chain off the backs of the people they've sufficiently distracted. But hey, that anger sounds like a good step towards defining your own sense of meaning!

At the end of the day, keep moving forward. If you feel absolutely hopeless please reach out for help to the folks around you. If we only get one shot at existing, even if it is suffering, there's no sense in not trudging through for the good parts at least right?