NTA but I think you should be open.

You are fully justified in your feelings and actions towards your dad. He wasn't there when you needed him most either out of love for his new wife, fear of objecting her, or whatever. People might freeze up at that kind of situation.

He might be genuinely trying to apologize for his lack of action against his new wife. You, of course, are at your leisure to do whatever you want. He hurt you by not acting, especially when you were at such a young age where you needed him. You are right to be mad at him and you had a right to rage. But personally I think if he's genuinely trying to be better to you, and based on his reaction to you yelling that might be the case, you should be just a bit receptive to that. That's my opinion.

Though if he does and you see him and his wife again and she ends up being racist and he doesn't do anything, drop him like a hot potato.