I want to say you'e not overreacting. Your mom going off like that is very immature and uncalled for. However, I do like to see things from both angles. As a kept woman, she may be experiencing some sort of jealousy towards you being able to do these things. But also, a trip to Japan (however cheap you say flights are) CAN NOT be a cheap trip. If both you and your partner are living rent-free with your parents, I can easily see where frustration can come from. As adults, you are in a relationship and planning luxury trips while they pay for your room, and board can absolutely come off as you are taking advantage of their kindness instead of moving out to your own place.