What do you think I need to do now?

I’m sorry that its a bit long but could you please help me? Alright, so me and my fiance love each other very very much. Close to the end of last year she moved extremely far away and she’ll be there for a few years. So all we do for the time being is talk on the phone for two hours or more a day and text each other. But in the last couple weeks I’ve become overwhelmingly busy and haven’t been able to talk on the phone as much. Yesterday I was in school around the time we call each other and before she would call me I texted her saying I might not be able to talk on the phone tonight and that I loved her so much. So she said okay and that she would talk to me when ever I got the time. So I said I was really sorry and she texted back “whatever”. I asked her what’s wrong and she then said “Nothing, I’ll just talk to you whenever you get the time like always”. I’m really terrified of losing her and the way she talked made her sound really angry at me. She wouldn’t normally talk like that to me. The reason I’m so afraid of losing her is because she left me once before, and some things happened after that between us in the year before we got back together. I’m stressed out about the whole thing and when I’m stressed I get sick to my stomach and want to throw up. When these kinds of things happen, it makes me feel like I’ve been a bad fiance and adds to my already depressed mood. I don’t know how to truly let her know that I love her with all my heart and that she’s my everything when she’s thousands of miles away and I cant even hold her in my arms or kiss her to make sure she knows everything will be alright. What should I do?