AITA for telling my daughter to hit below the belt?

My daughter is currently in the hospital, about to give birth to my soon to be grandchild.<br><br>This was complicate because my daughter was registered as a donor and miraculously the baby girl she birthed was a match for her younger sister. So they decided to organ donate and the surgery was a very complex one.<br><br>Before the surgery, both my daughter and my sister in law were heavily sedated. The doctor came out and told us the surgery went well and both girls are recovering well. He also told us we could see them in about 2 hours.<br><br>My sister in law cried and cried while I just sat there. Eventually I had enough and I said "Hit her where it hurts the most, she's making fun of me". <br><br>Turns out my daughter had a major fear of spiders and my sister in law had been hiding them around her hospital room. She put one on her bed, in her water bottle, even in her hair once. Every time my daughter asked her where the last spider was, all she said was "not this time, she's so fat now, she can't move". <br><br>My sister in law burst out laughing and I just stared at her. I asked her why she was doing this to my daughter and she just said "you told me to hit her where it hurts the most". <br><br>I didn't. I would never do something so low and dirty to my sister. More importantly, why the fuck are spiders in the hospital?! This just doesn't make sense. I didn't say anything but she's been giving me dirty looks all day.