I love someone and they love me back, but I have to leave forever

So, there is this one girl I started talking to during my last semester of highschool, we talked a lot, and we had a lot in common, I find her really pretty, and I think its the first time ive fell in love with someone like this. And thanks to some of my and her friends I found out she likes me back, the problem is that, this year I have to leave the country forever, and Ill never come back, should I let her know my feelings before I leave? Or is it better to not tell her so that she doesnt suffer, because, she has gone through really bad stuff before, and according to her. Ive helped her feel better. So I really dont want her to feel bad or be sad because I leave, what should I do? I NEED ADVISE ASAP please