Im so furious and this is probably outing but I need to vent. SIL clearly and brazenly having an affair with my brothers best friend, she is an absolute trollop. They only got married 6 months ago. My brother has asked her repeatedly and she's denied the affair despite stopping out all night every weekend for the last 6 weeks, coming home with love bites on her neck at 4am, spending all her time with this guy, out on all night benders with him every week. They both deny the affair. I can only assume shes swept up in it the romance/excitement all because she's not bothered about taking care of her kids, i'm so worried about them, she's out drinking all the time with this guy, taking the kids to the pub, the kids look unkempt when she is supposedly caring for them, the one has terrible nappy rash, rash all round his mouth. She told DB she wanted to separate 2 months ago, no explanation just that she didnt want to be a married mum of 2 anymore, then took herself off to hotel for the night for some alone time. She doesn't work (never has) but DB does and pays for everything. He's devastated. She's made him sleep on the sofa the whole time, shouting & screaming at him, spat at him, off on 3 day benders, coming home hungover, leaving the house in a state dirty nappies and empty beer cans everywhere, its awful. I think because she's embarrassed about breaking up 6 months after the wedding she's spinning a false narrative about my brother to justify her behaviour, the other day she went out all night came home very hungover at 8am ringing her friends that he'd taken the kids when he'd just popped to the supermarket to get them some stuff for breakfast. She really is vindictive and conniving. But what can I do? I probably won't achieve anything by calling her out on her behaviour, i don't want to lose out seeing my niece/nephews. I just think she is a vile person and hate seeing my brother so broken by her. I really hope what goes around comes around. I don't know how best to advise my brother to protect him from her because she's unhinged.