I learnt a very long time ago, smile and look as if you are listening and agreeing, then go your own way and say nothing. I never say anything to anyone in my family about another family member, because the rows I have witnessed have been over such simple things yet the repercussions have lasted for years. I have two sisters who haven't spoken to each other for years and one of them has only just started speaking to my mother again - and they can't even remember what the row was about, exactly! This has been very hard for me, because I am by nature very outspoken. However, I do have a brain... 
Thank heavens for places like this. I can tell you lot that SiL is a lazy slob, shoves ketchup on everything, won't eat anything other than roast and roasted potatoes and chips and bread, the only veg being Heinz baked beans, still hasn't put up shelves from 4 years ago and will never have a better job than the one he has now. If I can endure him coming to stay with me for weeks at a time, with my big mouth, I have great hopes for you Anya!