It's definitely mixed emotions,because you definitely feel relief that somebody that represents  and cruelty,that was responsible for the murder of my father,finally, the fact that he's no longer on this earth brings a justice to the situation.

这个句子确实结构较为复杂。分析如下：

It's definitely mixed emotions,主系表结构（主句）

because you definitely feel relief that somebody that represents injustice and cruelty,that was responsible for the murder of my father,finally, the fact that he's no longer on this earth brings a justice to the situation.主句的原因状语从句。其中：

you definitely feel relief 为because从句的主谓宾结构。

that somebody that represents injustice and cruelty,that was responsible for the murder of my father,finally, the fact that he's no longer on this earth brings a justice to the situation

为relief的同位语从句（relief后接同位语从句的词典例句：He expressed relief that the crisis was finally over.《韦氏高级》）。其中：

somebody that represents injustice and cruelty,that was responsible for the murder of my father为同位语从句中的左偏置结构。

finally, the fact that he's no longer on this earth brings a justice to the situation.为同位语从句中的主谓宾结构。主语为the fact that he's no longer on this earth，he指代左偏置结构中的somebody。

参考译文：

这无疑是复杂的感情，因为你肯定感到一种解脱，那个代表着不公正和残忍、那个对谋杀我父亲负有责任的人，他从这个地球上消失了这一事实终于给这个局面带来了某种正义。