People who don’t realize that your views may be different, will probably be taken back by an emotional outburst of opposing views, and no doubt will take umbrage, but why should you hold back, while someone else has their say? However, if you value the relationship on any level rise above it if at all possible. I know it’s easy to say but hard to do, but one alternative if you’ve had a bad day at work, is let her have it both barrels. It’s just politics and many people understand the “it’s nothing personal” clause. Have you ever watched say how the French talk. One minute they are talking normally, and the next they’re in a frenzy, but nothing changes as a result. If you’re going to be diplomatic, disagree by asking a poignant question that doesn’t confront and let’s the other person consider an opposing view without it being forced upon them.