If someone attacks me in my own home, and i defend myself with a crowbar, am I in the wrong?

If you mean will you face criminal liability, that depends on the circumstances.  You are justified to use necessary force to defend yourself, and if you're violently attacked by a 200 pound guy who broke in to your apartment, I don't think any one would contend that you had committ4ed a crime by defending yourself with a crowbar., especially if the attacker was armed  On the other hand, if you had already incapacitated an unarmed man by breaking his leg, and he no longer posed a threat, you could get in trouble.  If the "attack" was that he spit on you, and he was leaving, you could get in trouble.  If the "attack" was by your wheelchair bound 90 pound grandmother trying to spank you, you could get in trouble. There re obviously many factual variations which could change the outcome.