But in his mind he only did it for Maggie so she wouldn't have to, right?

Pretty much, yes.  I think he sees himself doing Maggie's dirty work behind her back, so that she doesn't have to get her hands dirty, so that she can keep her conscience clean.  Because, really, he sees himself as way past redemption, so what's a little more blood on his hands (especially the blood of some really bad baddies?)?