tl;dr
I agree with you (the bold). I like when people discuss interpretations. I think this is one reason I am a huge David Lynch fan.
Support for your angle: Andy created a fictitious "phantom" to receive the proceeds he was taking from the prison's accounts....so he didn't see breaking the law as a big deal.....later, he seems to justify his actions because of the prison library and the fact he is helping inmates with their GED and is getting the warden some "good press"...there's also that exchange in the library with Red when he's telling him about this fictitious persona, and Andy gives the impression it's okay to break the law as long as it doesn't really hurt anyone (my sense of what he was saying)....also the way he asked Hadley when tarring the roof if he thought his wife would "go behind his back"
HOWEVER, (see italics) Red is the one who tells Tommy that Andy's wife was murdered by some golf pro. And Tommy just HAPPENS to have shared a conversation with a fellow inmate who described to him that situation? Nah. That part is a stretch.
Andy is not a purely innocent victim, I agree, more an anti-hero, but my interpretation is that he did not kill his wife. But if Red had not been the one who told Tommy why he was in there, I might very well have that view myself.