A mentally & physically abused teen witnesses the murder of his family. Now an Adult, he enacts revenge on the entire family responsible.

The only thing you need to add is some detail around the family responsible.

Being specific in a logline that explains a well worn genre, like revenge. But you do get some free brain power from the reader because we all know what a revenge story looks like.

The abuse adds to the depth of imagine I conjure when reading a logline.

How does the mental and physical abuse relate to the murdered family or the murdering family?

The concept sounds interesting, but familiar, and a special twist would make it juicy.