Yeah, they get defensive sometimes. It takes a very careful form of tact in order to meet them on common grounds. Best way I've found is to come in, say you're a furry in order to notify them, but engage in conversation *peacefully and respectfully*, because it shows a willingness to communicate and engage in well-mannered discourse. That way, you're able to set the bar for the maturity level of the conversation, and so long as you're able to uphold that, most anti-furs will actually be fairly chill. After all, past all the jokes, threats, and controversy, we're still all just people. But if you're talking with an anti-fur, you have to show that by example, and set the bar. This is true with anyone, really. If you lay out your disposition as clearly as possible on the table, and then present a respectful discourse, you can set the tone for any conversation, which can help lead to a better mutual understanding.
Sorry, I rambled a bit. :P