My younger brother was visiting with his wife and kid. He’s been married about two years now and lives out of state, so I only see him about once a year. They are staying at our home. This would be the fourth time actually being around my sister in law, and she’s a very nice woman that my wife and I get along with well when we’ve seen her. The problem came when we were grilling in the backyard and decided to use the pool. SIL came out in basically a thong bikini. I didn’t think this was appropriate at all, but held my tongue as not to embarrass her, but I have a preteen daughter in house, and I can’t have people over dressing inappropriately in front of her. I talked with my wife about it that night and she agreed it wasn’t family appropriate, but said not to say anything to her as not to make things uncomfortable. I said I wouldn’t, but that I would address it with my brother privately because I can’t have our daughter seeing that in our home and thinking we approve. She said she preferred I just let it go, but I don’t think that’s responsible parenting. So the next day I spoke to my brother privately and prefaced that this might be an uncomfortable conversation, but it’s necessary. I told him my concerns and asked that he have her wear a more appropriate suit. He got a little offended and accused me of sexualizing his wife. I said that’s not my intent and it would be one thing if it was just us adults, but I have a kid in the house who were trying to raise with a sense of modesty and that I don’t want to normalize that kind of swimsuit in our house. Then he said “that’s just what they wear, it’s not a big deal,” which surprised me since we were raised in the same house. Not going to lie, I did feel like I lost a little respect for him being “cool” with such a display by his wife. Then he asked me what do I do if I go to the beach? I told him I can’t control everyone at the beach, but I can control what’s allowed in my home, and that when it comes to kids, what you allow you condone, and I’m not going to have my kid thinking we condone that. And especially since she gets along with her aunt, I don’t want her looking at that style as something she thinks is cool. He said he wasn’t going to tell her to change as that would be weird, but they simply wouldn’t use the pool anymore. I said fine, handle it however you think is best but I don’t want to see it again in my home. I also told him we won’t use the pool either for the duration of his visit so that no one feels singled out or anything. He ended with “fine, so you’re like Dad now.” I said I should be so lucky and left it at that. The rest of the visit went fine, no issues, but it felt like a bit of tension with me and my brother. So AITAH for how I handled this? I tried to do it in a way that would minimize the potential embarrassment for anyone but still put a stop to the inappropriate behavior.