Is it wrong to kill in self-defence?

You have misquoted. The fifth commandment is "Thou shalt do no murder." Killing that is not murder, such as in self-defense, is not forbidden.

I believe the meaning of the commandment is to not kill without a clear basis. It does mean that just because a person is not attacking you does not mean you shouldn't kill him. An example is a cartoon action show that I seen. Two girls have no escape from the attacking crowd. This crowd is controlled by another character who has special powers. Now, it's wrong to kill the crowd because they are just being controlled by the character. The scene changed with the protagonist ending up killing that character who controlled the crowd. Strange but it's how it played out.

[002:190] Fight in the way of Allah against those who fight against you, but begin not hostilities. Lo! Allah loveth not aggressors. the verse from the holy Qura'n clearly says that self-defense is permitted, provided that you begin not hostilities for Allah loveth not aggressors.

The commandment is not against self defenses, if your life is in danger and killing your enemy is the only way to keep yourself alive, then by all means, kill your enemy if possible. There is nothing wrong with that in the eye of the mighty God. The 'kill' here actually means 'murder', not self defense. On the other hand, if you prefer to die in the hand of a murderer or rapist than live, then don't kill and then blame it on the fifth commandment.

Of course it's not wrong to kill in self-defense. If deadly force is needed to not be raped or murdered, then so be it.

I would just go for laming rather than killing but if I killed the person I would not feel guilty. Even in the Bible day provision was made for an innocent killing. They had cities where you could go for protection until you could be proven guilty or innocent.

"Though shall not kill"can be a case to case basis, I think. Defending yourself is not a crime, but if you intend to kill the person attacking or harrassing you, then that's a different story. But if it's really not your intention to kill your attacker, and you just tried to defend yourself and you repent, I know the good Lord will forgive you.

Under Philippine laws, self defense is a justifying circumstance so the person who killed another one based on self defense can be freed from criminal liability. But this is really hard to prove and all the requisites must be strictly complied with. I am not sure how it works in other countries :)