I'm not studying Japanese, but doesn't this depend on the level politeness used? There is probably more than one way to say 'I hate you' in Japanese, which doesn't happen in English.

わたしは、あなたが_____ ( I assume that you know some basic Japanese sentence construction or grammars) These are the words for hate and/or similars 大嫌い 憎む

わたしはあなたがきらいです。 watashi wa anata ga kiraidesu. In mad mood. お前がきらいだ！ omae ga kirai da!

hate is very strong word. I think hate is stronger than "kiraidesu" I think "I hate you" is "watashi wa anata ga nikui desu." わたしはあなたが憎いです。 I think you'd better not use this sentence.