I really miss this girl:(?

I'm away on holiday for 4 weeks which started last week, I'm all the way in the US and the girl I miss is back home in the UK. I'm almost into my second week here but i miss her like crazy. She's not mine, but we are really close and I love her very much, we spent almost everyday together for like 2 months and we started to drift a bit, and I thought this long break from each other was what we needed, but she messaged me yesterday saying she was in tears upset because she missed me, which also reduced me to tears, and if this is how I am after one week, how am I going to be after 4? Obviously all I can do is look forward to seeing her, but can someone please give me some advice on how to get by?:(

Signed depressed 18 year old :(