We do not always agree so rather than stamp your feet - Be the Adult.
I see it every day in business, people get ticked off at someone and they start being negative and pushing back and the gap gets bigger and the device gets wider and most times it gets to a point of no return... be the adult.
If you lost it already with that person then swallow your pride and apologize, start again..find the bridge.
You do this for yourself as much as for them, it is so much easier to have allies when you go to work then enemies and it grows because people talk, Facebook, tweet, email..and before you know it your reputation has taken a hit. Rather you are right or wrong you spend your energy and time deflecting and being defensive and then you hit back..it is all exhausting.
Be the Adult and find a way to gain allies and do your job better, not once in a while but every day.