I'm going to tell my boyfriend his pet bird escaped, but the truth is that it died when my cat tried to eat it
Did you allow your cat to kill the bird?
It's not my fault the bird died. I tried to save it but the cat outsmarted me.
You should tell your boyfriend the truth about what happened to his bird. He might be mad, but it's better than letting him live on in anticipation that he might find the bird in the neighborhood.
I know, I just want to see the look on his face.
That's evil. If you hate your boyfriend that much then end it, don't lie to him.