My husband tells his family way too much about my personal life...

Been with my husband for 15+ yrs. I don't hate my in-laws, but we're not exactly close. We live about 5 hrs away from both our families but visit every few months. Last week was our most recent visit.

I've had a few health things going on lately and no one knows aside from my husband and doctors. One biggie is gynecological. I keep these things to myself as I don't want others to be unnecessarily worried nor am I a fan of broadcasting my personal info. My parents aren't well and don't need to be saddled with worry, which is also why my older sis and twin bro don't know. My gyno is treating me with a medication that has a side effect of weight loss (no complaints here!). I've been taking it for almost four months and have lost a little over 20 lbs with it and dietary changes.

I was having a particularly rough day when we'd planned to visit his fam (we stayed at my parents' house) and asked him to go without me. He was fine with it. Couple hours later, I was lying down and my phone rang. It was my SIL asking for the name of the medication I was using "to lose weight" because she has a friend who is a NP and would write it for her. I was furious but told her since I was put on the spot. I had to jump through a million hoops just to get my insurance to cover that med.

I confronted my husband about it later and he didn't see that he did anything wrong. I asked how she came to know. He said that they'd asked why I wasn't there so he "had to tell them." I told him that when his sis asks for that script, it's going to pop up for its primary use and they'll all know. BTW, his mother, one sister, and others are addicted to opiods and love to know who takes what. Husband and I have both been asked for leftover pain meds from prior surgeries over the years.

I was in a lot of pain and got agitated, but am I wrong to be upset? I feel like all he'd have to say was "Katy's not feeling well" and it would have been fine. He's told them about the meds I take regularly, including one that is specific to a different issue and others like my anti-anxiety meds and I don't like that. I feel like it's my business alone. I am very much an introvert and that was his excuse. Is it just me? Is it because I'm an introvert? Am I not seeing that this is harmless? How can I handle this? I can't talk to others as I don't want to disclose the issues I'm dealing with and apologize for such a long post, but I need advice.