What is the french word for the feeling when you end your vacation and start to head home?

Zut!

As-salamualikum sis, I think it's a very big transition for you since you have a family who sounds like are devouted christians to me. But i think what you are about to do (convert to Islam) is the right thing and i can promise you that you'll never completly regret doing this in your life if you put your heart into it. I think you are independent and brave enough to make your own and the right decision. Don't be mad at your mom though becaz she doesn't know the true beauty of Islam... yet and I totally see her point becaz my mother would have been upset aswell if i told her i was converting to christianity. She would not tell me that she is going to kick me out of the house but she would make lots dua for me and try to talk me out of converting. Anyways, good luck with everything and may Allah help you make the right choice and give you lots of courage.

Merde!

Not quite what you mentioned but I usually end up saying "c'est la vie!"

Adieu...Adieu...Adieu.... with tears in your eyes)