可惜你家离我家太远了

Which stands for the fact described in the sentence(Your house is very distant from mine), so I will use 这件事（this event) to replace which. here it is 你家离我很远，这件事真不幸。

Translating is not about using every single word, it is about getting the meaning across! You have to think in the target language, you can not translate word for word. If I said this in Chinese I might say: 不幸的是，你家离我很远。, Or I might say 你家离我很远，真不幸/真可惜. I would not even use the word which..,