I think it depends a lot on the details of how your skip level boss asked, and what exactly you said. It's not reasonable to expect you to lie to a superior to cover for your boss. If you went out of your way to give them dirt that's another thing. The whole situation sounds really toxic. In a healthy organization your boss's boss would use the information you provided to help your boss get through this rough patch. Upper management at your company is probably terrible. You should get another gig, this situation is not going to get better.

What field are you in? Your old boss sounds like a superhero. I suggest you reach out to her, come clean, and apologize for your part in the situation.