I think you answered your question in your last paragraph -- you need to agree on why you're playing the game in the first place. It seems you weren't aware of your different philosophies until now - okay, there's a first time for everything. Now that you know this, you can handle it:
Before you play each next game, agree what the point is. There are two ways to play games:
- If you're playing one round in a game that is part of a long series then it makes sense to keep the rules strict, or else the total standing in the series doesn't mean anything.
- But if you're just doing a single round of a casual game, the emphasis is probably more on the enjoyment and the laughs.
There's a time and a place for both styles. I have been in similar situations and had big arguments over game rules and objectives. The lesson I've learned is that I need to know what the other players think the game is about: winning or having fun? I'm pretty laid back and would agree to bend the rules a little so as to give weaker players a second chance; for me, the primary purpose of a game is the social aspect, not the competition -- unless the competition is agreed in advance! Then I will tell you exactly what the rules say, but then it's not fun anymore (and then why would I play?).
In your specific situation, I regret to tell you that the mistake is yours: if you don't block another player while you have the chance, and leave the decision to another player, then it's out of your hands and you must accept his decision.
He decided to teach you this lesson, and you ended up learning even more than he intended! I would tell him that he did nothing wrong to make his parents angry. In fact what he did with his move was kinda cool -- praise him for this!
You should focus on learning from this and looking forward to your next game. Chalk this last one up to experience and avoid blaming yourself or anyone else.
Edit: So much for the specific situation. In more general terms you should not let things escalate that much. A loud argument is usually not productive so when you realize that you are having an argument, it's incredibly useful to defuse the situation by backing down. You're not "losing" by doing that.
Especially between spouses, one should always be able to say "let's not get carried away" and suggest to discuss it calmly, perhaps some other time when everybody has had some time to think it over. After all, your argument was not about any fundamental topic (just to name an emotional and serious example, think circumcision). It can also be helpful to offer an apology for getting carried away - it takes two to argue, and one of them is you.