Husband's Best Friend and Sister-in-Law's Suspicious Behavior - Am I Delusional?

I've been feeling uneasy about my husband's best friend, Chloe, and my sister-in-law's behavior. Every time Chloe comes over, I can't help but feel like there's something more going on between them and my husband. They seem too comfortable around each other, always laughing and whispering in each other's ears. My sister-in-law always seems to encourage their closeness, almost like she wants them to be together.

I know it may sound crazy, but the signs are there. The lingering glances, the secret texts, the late-night phone calls. It's as if they have their own little secret world that I'm not a part of.

Am I delusional for thinking this? They're just friends, right? But deep down, I can't shake this feeling of unease. It's like a gut instinct telling me that something isn't right.

I've confronted my husband about it, but he brushes it off as jealousy or paranoia. He says I'm overreacting and that there's nothing going on between him and Chloe. But why does he get so defensive whenever I bring it up?

I don't know what to do. Should I trust my instincts and confront my sister-in-law about her intentions? Or am I just imagining things? I need some advice because this situation is tearing me apart.