Respect

Okay, so I got into a huge fight today with someone pretty important, a member of an extended family of sorts. This fight was about political stuff on Facebook.
Now, my general policy is that if someone posts something that I disagree with, I ignore it or mumble something under my breath. But I never, ever go on to someone's personal page and tell them that they're wrong, or anything like that. For the most part, they seem to do the same for me.
But there are a couple of people who feel the need to post sarcastic, antagonistic, or otherwise disrespectful comments on things that I post. I may argue with them for a bit, but for the most part, I try to ignore them because I feel like they're deliberately baiting me.
Today, a person attacked one of my friends because of a comment my friend had on a post of mine. And I couldn't take it. This person's comments lately had been increasingly anatognistic, and I was getting fed up. So I sent a message saying (to put it succinctly), "Listen, you can disagree with me all you want, but please don't come on my page and attack my beliefs or my friends. Please show me some respect." And this person started in on me how I was completely disrespecting America and a horrible person, and I didn't respect anyone else's opinion, and so on.
Now, this annoys me. Because clearly I do respect other people's opinions, as I never attack anyone else's posts. I have been sorely tempted, but I never do, because that's freaking rude.
Plus, the whole point of this country is that we have the ability, the responsibility even, to dissent when we feel our government is wrong. Look at the Declaration of Independence.
And the simple fact of the matter is, that during this contentious period of political history, everyone is dissenting. Everyone feels wronged by our government. Some people hate the things Obama has done, some people hate the things that the Congress has done or is trying to do, some people hate other things. That's the one commonality we all have, across all divisions of ideology, class, race, gender, and sexual orientation -- we all feel like we have been wronged by our government.
I don't mind having a conversation with someone of opposing beliefs. I have no problem with that at all, and have frequently found myself changing my mind about something due to something that they said. But the way to have a conversation is not to attack someone and say that they're stupid and wrong for believing what they do. That is disrespectful.
Needless to say, the fight with this particular person didn't end well. I don't know what the future holds. On one hand, I feel terrible that I kind of started this argument. But on the other hand, I feel good that I loved and respected myself enough to demand that I be treated well. That's big progress for me.
So, I welcome respectful discussions. Did I go too far? Did I mess up? Let me know. Respectfully, please.