Couple Ends Their Vacation Abruptly After They Are Repeatedly Stuck Playing Babysitters For 3 Kids

My brother and sister-in-law invited my wife and me to join them and their three kids (ages 3, 7, and 10) on a vacation this week. When I say “invited,” I mean they asked us to come along to our parents’ cabin—no expenses were being covered on our behalf, which is important to note. Also worth mentioning: my wife regularly watches their 3-year-old three to five days a week (it’s supposed to be three, but they often drop him off more).
We all headed to the cabin together, and on the first night, they asked us to stay in so they could have a date night. No problem—we were happy to help. But the next day, things started to feel off. Their 10-year-old wanted to do something the younger two couldn’t participate in, and my brother and SIL decided to take him, leaving the 3- and 7-year-old behind—without even asking us first. SIL just popped her head into our room and said, “We’re going to go do [activity],” and left the younger kids downstairs. We were upstairs getting ready for the day and suddenly found ourselves unexpectedly on babysitting duty.
Later that afternoon, my wife and I decided to go bar hopping and have some fun of our own. SIL was clearly annoyed and said, “I thought this was a family vacation,” which felt pretty hypocritical considering they left their kids with us for four hours earlier that same day without warning.
Regardless, we went out and came back buzzed. My brother made a snarky comment about us probably being hungover the next day (we weren’t). The next day at the lake, my wife and I grabbed some drinks, and SIL pulled her aside to say she didn’t think we should be drinking while “watching the kids.” At that point, I’d had enough. I reminded my brother this wasn’t their vacation that they brought us on—we were all here for free—and if they expected us to act like unpaid babysitters the entire time, they should’ve said so.
So my wife and I decided to leave and book our own place for the rest of the trip.
Now SIL is sending us pictures of the kids and saying they’re sad we left, and she and my brother “don’t understand what went wrong.” From our perspective, we came for a vacation, not to be nannies—especially since my wife already helps them out so much during the week without charging a dime.