I see that life's being really awful to you right now. I'm sorry, and I completely understand your pain.
I know you stumbled upon this letter because you were trying to distract yourself from overthinking, but unfortunately distractions never really help. No matter what you read or what you spend time on, you're going to have to face reality eventually, and you're going to hurt. Unfortunately, running away from problems, or finding some sort of outlet or vice, never fixes the fact that life is unfair sometimes. Right now, it's pretty much awful, but it's not the end and you're much stronger than you know.
Okay, so maybe you won't trust me or actually listen to me, but honestly if you take a second and look back at all of the troubles you've had in the past, or even in this past year, you've successfully survived. Congratulations! One thing I like to do is to imagine my younger self and wonder how she would feel if she saw the "grown-up" me. Take this moment and realize that your old self is really proud of you right now. In this moment, right now, you've made it through every time you said "I don't think I can take this anymore" or "I can't handle this."
I completely know how it feels to feel overwhelmed with hardships and to feel so defeated that it's hard to continue, but we both need to realize that one day, none of this will ever matter. In five years, when we have new problems and new success stories, this was the time that made us into who were meant to be. Sure, the world's a mess and the year has been filled with extreme highs and lows, but you are ready for the future because of the problems and chaos you've experienced.
So, if you've been hurt, let downs, disappointed, or stricken with grief, let it hurt. Just let it hurt and let your pain radiate, because it's never going to heal if you don't face it head-on. Just like if you down acknowledge physical pain, it never gets better because you don't fix it. Ignoring your struggle and ignoring the pain will only make it last longer and make it hurt 10x worse.
Love your struggle and your path. Sometimes it's supposed to be hard, if it wasn't hard everyone would fly through life all willy-nilly, with no risks and no improvement. We'd all be the same. Our struggles define us and truly make us who we are.
All-in-all, listen to a sad song, write down how you feel, talk to someone you love, or just, cry. This is your time to heal and to trust that this is how everything is supposed to go. And when you go to sleep tonight, take a moment to breathe and realize that you made it one more day.
"Strength and growth come only through continuous effort and struggle" - Napoleon Hill