Your dad sucks, and his side of the family sucks. They've clearly set up your half-sister for massive disappointment. You are NTA here, they are.

That said, I strongly suggest you send your half-sister a card. The way your dad is handling this, it sounds like he'll blame you for not showing up. This isn't your fault, it's his. You don't owe him anything, but she's innocent in this, and it takes very little effort to send a card that says "hey I'm sorry they lied and said I'd meet you. I still have very raw wounds about what happened with my parents, and I'm not comfortable with this situation. Maybe sometime in the future when wounds have healed we can meet up, but I'm not ready to do that this year."

I'm saying this because I was in a similar situation and did as you did. Then, about 8 years later when my half-brother was in college, he realized how awful our mom was and needed someone to talk to. I didn't meet him until he was 19, but we're super close now. He told me he had hated me growing up because our mom painted me as this awful person who never came by for holidays. So like, let her see in your own words what's going on. Maybe you can meet up sometime when your dad fucks up again and she needs someone who's been there. But you'll be meeting on your terms, and not his.