I have said it here before and I will probably say it again: (as someone with crazy relatives before moving)
The only person you can control is YOU.
You can give your mom or dad all the comfort in the world. You could sacrifice your happiness and stay in the US. You can be depressed because of their attitude and actions. You can beg them to be happy for you. You could be the best daughter in the world until you leave.
None of it will make any difference unless the person wants it to. And clearly, right now, your mother, father, friends, whoever, don't want to feel better.
It is hard to accept, especially as women since we tend to be taught that we should make everyone feel better (especially when you become a mother) but honestly, you can't and it isn't your responsibility to do so.
We are talking about grown, healthy adults who have the ability to set their own moods.
It might be different if the person in question has metal health issues, but even then you couldn't control that either. Kids are also different, of course.
I, random internet poster, give you the right to be free of guilt associated with others feelings (within limits of course, don't go killing anyone's dog!)

It takes a while, but you can get there.
I have a rule, if someone is being totally negative and they will not stop (within reason again), then I give them three chances if it continues I leave the room or hang up the phone. Even when I was stuck living at home. If it meant going to the bathroom and locking the door, or putting on headphones, or picking up the hpone to call someone, then that is what I did.
Good luck!