It strikes me that the underlying cause of your unhappiness is not the professionalism or otherwise of the person that got the TA position, or the impact of his behaviour on you, but the fact that he got the position you wanted and that seems unfair to you. Here's a lesson that will serve you well I think: life is not fair. The world of work is not fair. Career progression, in particular, is not fair. Good things do not automatically go to the most deserving. If you want something, do not sit back and wait for it to fall into your lap because you think you deserve it for working hard or whatever.
Rather than focusing your anger on him, you should ask yourself: who or what is responsible for this state of affairs? Some helpful information would be to know whether you made your desire to be TA known to the advisor - if you didn't then you must have been hoping the advisor would simply offer it to you. Your colleague meanwhile made his desires to be TA known. Why shouldn't he? Did you really think that he should not pursue his ambitions out of some sort of deference to you because you have better scores? If he (or you or anyone else) adopted that policy they would never get anywhere in life. If you think he should not have been made TA and you should AND the advisor knew of your desire, then the responsible party is the advisor for picking someone else. If the advisor did not know of your desire then either you are responsible for not making your wishes clear, or your advisor is responsible for not asking you whether you wanted it before giving it to someone else. In either scenario, your colleague is not responsible for "depriving" you of the TA position.
So, if you feel something is amiss with him being made TA, talk to the advisor.
With the day-to-day behaviour of the TA it's a different matter - if you are not happy having work pushed over to you in this way then talk first to the TA about it, and if that has no effect talk to the advisor about it. Sitting there complaining and making accusations behind someone's back isn't particularly professional either. If you want things to change, start asking for what you want.