There isn't really a good argument to defend yourself. You knew that James had some problems, you noticed that something was wrong, and still ended up dating him and move in with him.

It took you three months to find out about his... Victims. He hid it well, until now. You also suspect that he made you discover it intentionally, but you're not sure.

You're too scared to actually leave. He won't take it well, that's for sure, you fear that you might become his next victim if you try to. And like that, you became his accomplice. Doing small crimes for him, helping him prepare stuff for his "work", all out of fear.

"Here you are," James said, opening the door of the bedroom and finding you in there. "I need some help for something."

He walked over towards you, lifting your chin with two fingers. "You're gonna help me, right, love?" He knows you fear him, he's using it to his advantage, of course. A good little and obedient weapon.