It's shades of gray. There is no complete black or white, good or bad. What you are doing is creating a multi-faceted character, and to me, that makes it far more interesting, and adds depth and interest to your game play.
I created a light-sided Sith. She is Level V light side, level 50, and far more interesting to me than if she'd been fully dark. Did she make dark choices along the way? Yes, but in the end, her light choices outweighed the dark, and she earned her Pure title, although she does not wear it.
I am going to create a Jedi and do the same thing, but in reverse, like your roommate. The Jedi struggle against their dark tendencies, so it makes sense for some of them to be anti-heroes, just as it makes sense for some Sith to be anti-villains and to see a different path for the future, however fruitless their hopes may be.
There are no Anti-Hero---Anti Villans, You are or you aren't. If you are not a Hero of the Sith Empire you are nothing you do not qualify and only quantify as a worm to be trod upon in order to improve upon the Empire. Or you are Republic trash and deserve only death