I hurt people physically when I'm angry...?

[SFE]

Well to be honest, it's not your fault that your 8 yr old sister is a brat.
Where are your parents? They should be aware of her behavior issues and should be raising their children.

Pushing her away/up against a wall after she hits you (probably as hard as she can, trying to hurt you even if she can't) is a reasonable reaction. I feel like I would do the same thing lol (not saying it's the best way to handle it, but it is understandable).

Now, forgetting about your sister for a second.. it's a very big step for anyone to admit they have a problem or they need help, so GOOD FOR YOU. If you think you need some help with 'anger' or controlling your emotions there are a few options for you:

You can ask your parents if you can talk to a therapist, psychologist or psychiatrist to help you out.
You can ask your family medical doctor for any advice/help he can offer OR for a referral to the proper professional.
You can speak to counselors at your school.
You can look up (on google, or facebook/other social network) local support groups (people who feel like you do, that they have some trouble controlling anger etc.) where you can be surrounded by people who understand what you are going through and who can offer their experience/advice.

Back to the brat...
You need to speak to your parents about her.
Stealing? It is absurd that an 8 yr old girl is stealing, your parents have clearly failed.
Stealing from family is a disgusting habit that a little girl should not already be forming, and if she doesn't learn right from wrong she won't have a very successful life in the real world.
Hitting? 8 years is old enough to know right from wrong. She has to know hitting is wrong, bc if she did it at school she would be punished. She SHOULD be punished for hitting at home.
Seriously, are you raising your sister alone? Because it's astonishing that any adult can allow this to happen.

Tell your parents when your sister steals/hits, and they should punish her for it.

You could go to/call the local police station, ask if they could help teach your sister a lesson with you...
If you can bring her in or if a cop can come to your house for her "stealing" from you, and a police officer could "scare her straight".

My dad had a police officer scare my sister into wearing her seat belt (I wasn't born at the time, but I've heard it many times) bc she would often refuse/fight and take it off while they were driving. She still remembers that day every time she gets into a car, and I've never seen her without a seat belt.

If you parents refuse to punish her, I honestly have no idea what else to suggest... maybe YOU punish her.. if she steals from you, you take something of hers and hide it somewhere she can't access it. if she hits you, take away her toys.

Do you have your own bedroom? If you find yourself getting frustrated, go into your room/lock your sister out.
Depending on weather and where you live, you could go for a quick walk or go to the park just to calm down (it works for me sometimes!).

Raising your sister and making sure she turns into a decent human being isn't your job, your parents need to raise the children they brought into this world.

This is exactly what is wrong with the youth today...
their parents don't give a crap about them, they don't teach them manners, values or rules and then they expect the rest of the world to put up with it..

If your sister doesn't get punished, she won't learn the lessons she needs to to be a decent human..
This will affect her for her entire life..
She won't have good friends (maybe some trashy friends who steal)..
She could get herself into a lot of trouble behaving this way with people OUTSIDE of her house, she might get beat up, badly for trying to steal from the wrong person or for trying to push around the wrong person..
She could go to jail..

Do your parents not care about her future at all? Where are they?

Maybe you can call Children Service/Childrens Aid, bc your parents clearly shouldn't be allowed to have kids in the house.. you and your sister depend on them, and they are letting you down big time.