It takes two to have an argument, and of one party stops responding or just says 'well, I've said my piece on this one so there's no use just repeating it ' then there is no argument. Are you actually arguing or having a discussion where the two of you take opposing sides? Are you upset/offended/annoyed by him or do you just disagree? How did he find out about this refusal to give your OH £5k? Did you tell him or your partner? I would have thought that offering information like this to someone you already know you clash with is a recipe for disaster, so perhaps you could try to avoid sharing this kind of information with him if you know it's likely to lead to a disagreement. It's also worth considering whether either of you wind each other up on a topic that you know you disagree about - who usually brings up the topics which instigate the arguments? To be honest, in laws are just like anyone else from colleagues to friends' partners - you either have to find a way to get on with them or avoid them. It's not reasonable to expect not to see your brother in law, so you need to find ways to navigate around topics which will cause an argument, keep your cool and pick your battles. If he makes sexist/racist/inappropriate comments and you can't bite your tongue, say something like 'You know my feelings on that, so I can only assume you're trying to wind me up which won't be happening today' and leave it at that.