meeting SOs friends 🤔

So my SO has a female coworker that he's told her about us, we're married, pregnant, what we argue about etc. At first it was like okay don't care. They call each other brother and sister and they just met. And she wants to overexcitedly meet me and go with me to buy baby stuff, she calls our baby her niece or nephew. And it's weird as hell to me. Because I haven't met her. And she and my husband just met. And my husband acts like I'm overreacting when if the shoe was on the other foot he wouldn't like it. So I'm confused am I just feeling like this because I'm super sensitive being pregnant orrrrrrrrrrrr am I justified???Â