Alright, so today started out as my very good friend slams her head against the table complaining that what she was mad about was for a stupid reason. Well she then went on to say something that scares me, "My girlfriend doesn't even say she loves me anymore." And her girlfriend was right there. She then went on saying, "Why are you here? You don't even care about me." And lets just say I can't tell her I love her. Later on, I met her girlfriend and was informed of her cutting herself last night and that she will be breaking up with her girlfriend when she moves. GOD! I know it's none of my business but it rubs off on everyone and me!

Also, there is this damn ass girl who is the person I absolutely fucking hate! I can always hide my fucking feelings of hate behind my mask of "the happiest child in the world!" I absolutely hate that I am admitting this right now, but it's important. See, the reason I hate this girl is because she ruined my life, no joke. I beat the shit out of her in elementary school. Moving back to the present, we have this joke of calling each other derps and scaring each other for heart attacks. Well she allowed me to punch her and when I did, she immediately changed into "I will be happy with the fakest ass smile in the world!" And then she began avoiding me! She won't even let me talk to her to apologize! And her friends are noticing it, and when I told them they all said, "oh, that explains her attitude."

What the hell do I do!? It's killing me here!?

Looks like we have a bit in common, with the only difference being our gender.
my GF recently went through this before we started dating, and I did a few years back.
The shit friends and relationship destruction go hand in hand.
those vibes might be assisting this.
as for the solution, you need to be there for your friends who are breaking up and avoid the one you can't stand untill you can get along with her.
above all count your blessings and stay positive.
you're not the only one who wears a mask.
just know you're not alone.