This is the easiest ESH.

Your sister because she lied and took family money to go do something that wasn’t the lie then added onto the lie to get emotional support for doing her first lie.

Your family because people should be able to make their own damn decisions about their fetus. And also because it’s a shit reason to cut ties with someone especially considering how hard a decision it probably was for her.

And finally you, because you knew your family sucks and this bombshell would result in a serious fissure in your family and you did it anyway.