What are the repercussions of not apologizing to someone you've harmed?

[Ashes]

I've been a horrendous big sister (though I know I could be WORSE). I was just miserable towards my little sister 24/7 (I'm 17, she's 12). Once, I raised a knife at her and made a quick downward motion, at which point she jumped in fear that I would actually stab her. Another time, she was making fun of me on a very sensitive subject, and I threw something at her then began punching her repeatedly in the chest (this was my third or fourth time ever having a blacked-out angry episode). Then I started cussing at her, something no one in my household does (except my parents). Another time early this year, she decided to embarrass me on the bus (I said NOTHING at the time, because I didn't want to embarrass HER in return). That lead to another explosion when we got home. We don't speak any longer.

Only pride is keeping me from apologizing. I think God is punishing me by making me feel depressed and sick every time I think about the awful things I've done. I think she knows I love her, because we have a very verbally and physically abusive mother who decided to slap her in the face with all her strength, at which point I snapped on my mother (and this is during the time that my sister and I weren't speaking, yet I defended her) SHE didn't cry, but I definitely cried for her.

I'm homicidal towards my mother because she is the epitome of damaged goods. I HATE her with everything in me and I would really like to witness her dying in an inferno, at which point I'll take comfort in the fact that she will most definitely descend to hell following her demise. I recently came to the conclusion that I need to start over. I'm GONE when I turn 18. I want to forget about my entire family (family doesn't mean sh*t, they screw you over like anyone else). I'm determined not to even THINK about them when I start new. I won't look them up, and I'll cut off all connections to social media. However, I fear that guilt towards my little sister will keep me chained to my house. I fear that God will punish me if I never apologize before I leave, though at this point, my absence would probably benefit her. Would it be cruel of me to neglect to say the word "sorry", even though I've said it in subtle ways like buying her things, sticking up for her, and telling her I don't hate her?

[Karel]

Eternal suffering in a lake of burning sulfur.

[Fireball]

they might avoid you forever...see relationships
see a shrink

[SmokeUpSerling]

Withholding forgiveness or apology hurts you more than the one you fail to forgive or apologize to. Bitterness will eventually take the place and root into your joy and choke it out like weeds. A good gardener tears out the weeds so the fruit of goodness and righteousness can grow. Forgive the trite analogies, but I found this to be true from first-hand experience.

[Chris Land]

james 4 and 1 pet 5 says god gives grace to the humble. whenever you humble yourself you are putting yourself in a position to be blessed by god. groundwire.net

[LadyB]

We make our own karma. Make yours good. Let your conscience guide you.

I believe you should look into getting some counseling, because you sound like someone who is becoming her own mother and I'm sure you don't want to end up like her.

You need some healing and so does your little sister....