Kett makes a very good point. If Mrs. HD's whole premise is that you are selfish, and she has not been able to deter you so far from taking the trip, then she has to up the stakes. She has to create a situation such that if-- in the face of whatever-it-is-- you still decide to go, you will prove that you are selfish.
The nonrefundable ticket will not change the fact that you are the most selfish s.o.b. on the face of the earth, but it might make her say, "Well, then go so you don't waste the money! But I won't forget this for a long, long time!" Anyway, at least you will get to go.
I DO NOT see her changing her mind and deciding it is okay for you to go with no adverse consequences. You WILL be punished.
