Okay so this is actually really gross when you think about it. That’s your husband’s literal brother, like they came from the same family and this dude is out here trying to wife you up? That’s so weird and disrespectful on so many levels I don’t even know where to start. Like, blood should mean something and this guy clearly doesn’t care about that at all. He’s not just disrespecting your marriage, he’s disrespecting his own brother which honestly makes it ten times worse.
You need to shut this down immediately and I mean right now. Don’t be nice about it, don’t sugarcoat it, don’t leave any room for him to think he has a chance. Sometimes guys like this will take the tiniest bit of politeness and twist it into “she’s just playing hard to get” or “she’ll come around eventually.” Tell him straight up that it’s never going to happen and that he needs to never bring it up again. And then you need to tell your husband because keeping this secret is only going to blow up in your face later.
I know telling your husband sounds terrifying because what if he doesn’t believe you or what if he blames you somehow. But imagine if your husband found out later that his brother hit on you and you hid it from him. That looks way worse honestly. Like, what are you hiding then? Just be straight up and say “your brother said something completely out of line to me and I need you to know about it.” If your husband is a good man he’s going to be upset with his brother, not with you. And if he does get mad at you, that tells you something important about your marriage too.
After all this goes down, keep your distance from the brother. Like, limit conversations to hello and goodbye at family events, don’t be alone with him ever, and if he tries anything else tell your husband immediately. Some people have zero boundaries and you have to enforce them yourself. Family gatherings might be awkward for a while but that’s 100 percent his fault not yours. You didn’t ask for any of this so don’t feel guilty about the fallout.