Some people are just obtuse. My husband and I rented a cabin in a ski resort area for our honeymoon - my niece and her husband took our toddler for the week and off we went. My husband's brother happened to be at the same resort (he had no idea we were there.....he doesn't pay attention to anyone else's plans) at the same time with his girlfriend and when their dad realized we were at the same place kept suggesting we get together and hang out. While my husband and I were there on our freaking HONEYMOON. Luckily we didn't even know that they were there at the same time until after we got home because my BIL's gf immediately said they were absolutely not going to contact us or try to get together with us because we were on our honeymoon (thank heaven she had some sense there - I guess they saw us twice and she insisted they go the other way so we didn't feel obligated to hang out). Then when FIL was telling us that he kept encouraging my BIL to get together with us he got offended when my husband immediately asked him why he would think we wanted to spend time with any family members on our honeymoon. It also turned out that his dad told other family members that live near there that we were going to be in the area and we should get together (they also left us alone). Honestly, knowing his parents, I'm surprised they didn't offer to let someone stay in the cabin with us .
Am I the only one that is wondering how extreme of an alarmist you have to be to insist someone go to a hospital for nausea and lightheadedness? Regardless, your SIL is a major a**hole........this was not her news to tell and you deserve a massive apology.
I used to love dogs........I have always loved them more than I like most people. THEN I had kids. Now I can honestly say that they mostly annoy me, at least right now while I have toddlers and I don't want anything else around me that is constantly demanding attention and needs to be taken care of (turns out this is common after having kids). It is safe to say that if we had not had a dog before having kids I would NOT agree to getting one, and I definitely will not get another one. Dogs especially need SO MUCH ATTENTION and I don't currently have any to give, and this is more annoying for me than my husband because I'm home all day while he gets a break from little people and canines getting all up in your business. NTJ for not wanting one more responsibility added to your plate.
Is she reckless or just plain stupid? You need to assess whether or not you want to be in a relationship with someone that has such casual disregard for common sense and general safety, because now it isn't just her own safety she is putting at risk but yours, too. What if you have children? Can you trust her not to pick up strangers with them in the car?