Homesickness is exactly the right word I think. Like an ache for a place that no longer exists (and maybe never did). It is akin in my mind to not being able to return to your war-torn country (even if you went back, your home isn't there) but catching glimpses here and there of something familiar that is both soothing and wrenching. It is lovely, but reminds you of what you can never have. You can adjust and even thrive, but you'll never not be a refugee.