You are not a horrible person. But, seriously, its a funeral. He has to go. Well....he doesn't have to go but if he wants to be there, let him. Funerals are really important. I get the money thing, but that's life. Sometimes shit piles up all at once. Yes, you'll have to pay off the credit card and that's some bullshit but that's why credit cards exist. You pay for the convenience of 'now' with the hassle of 'later'. Unexpected relative death is a pretty good reason to pop out the visa.
There are compromises to be struck. Have him find a friend who will drive his ass to the airport. Tell him that, before he goes, he has to clean [whatever project you despise] and wrap a significant pile of gifts. Even a funeral and a viewing only adds up to two days. Can the flights work out so that he leaves after the funeral and catches a flight right back home again? Could he just go to either the viewing or the funeral? Do not, DO NOT, cancel your girl's night. Leave early if you must but make sure you get to go out and see some friends.
Or....maybe this is a time to talk to him about why he wants to go. Sometimes we go to funerals because we feel obligated, because we feel like we're saying we didn't love someone enough to make the trip. Maybe there are other ways to get that message across that don't involve him flying across the country. Flower arrangements are one, but maybe he might want to write a letter to the children (if there are children) telling them cool stories about the deceased and the times they shared. That would probably mean much more than him showing up in a suit. Maybe the two of you can brainstorm a way to celebrate her life in the home that doesn't involve a cross-country trip. Maybe you two get a bottle or two of wine and sit up late talking about his aunt and toasting her together. After all, the body itself is just carbon. The funeral is about coming together to honor her life and to mourn her passing.
I am so sorry. The timing of all of this sucks. But you'll find a way and no matter what happens, in ten years this will be absolutely unimportant. You will get through this.