How do you say Lẽ ra tôi đã đi dự tiệc, nhưng tôi bận quá. (Tôi đã muốn đi dự tiệc, nhưng không được vì bận quá. Nếu tôi không bận, thì tôi đã đến bữa tiệc rồi) in English?

I would have gone to the party, but I was really busy. (= I wanted to go to the party, but I didn't because I was busy. If I hadn't been so busy, I would have gone to the party.)