Am I going to be in trouble with law if I killed someone who broke into our house and beat someone who lives in there?

If you are attacked in your home you can kill the burglar and you do not have to retreat or even be attacked. The minute they break in you can kill them. You cannot use a gun if that is a crime to possess it but you can use any other weapon. You do not have to retreat from your own home. You can also kill them to prevent an assault on another if it is a serious injury situation. It is better to run away if possible because several men will overpower you even if you stab them and a woman cannot usually fight off a man even with a weapon.

A person can lawfully repel an attack, by using reasonable force under the circumstances. You may also use reasonable force to protect another innocent person against attack. What is reasonable? That is up to the police first, then the prosecutor, then the judge, then the jury. A deadly attack may be repelled by deadly force, if it was reasonably necessary under the circumstances. Beating someone up is unlike to result in death, hence, in most cases it would not be reasonable for you to use deadly force to stop a beating by fist. However, a case held it was reasonable for a woman to kill a man who was raping her. There are no simple answers here. Since the attack is over, you should report the illegal conduct to the police.

You have a right to protect yourself, your roommate and your property with reasonable and force. For more details seek counsel. It is not all that simple.

If you are in fear for your life or the lift of another, you may use the force necessary to protect you or the other. The level of fear must be the same as a normal person would feel if in a like situation. Because they were in your home and attacking your roommate, it is reasonable to use a knife to protect yourself or your roommate.

You can use deadly force when it is reasonable. That is in order to defend your self or others from death or serious bodily injury.