Keep in mind that hate is not the opposite of love: it's love spurned, turned sour. That's heavy stuff, so it's understandable to be overwhelmed. One thing that isn't clear to me: did she say this aloud, IM it, or text it? The tone of voice gets so easily lost in text. If she said "I hate you" in passing, it would probably mean something more like "I hate that you can't be here right now" -- a fairly innocent response in a long-distance relationship. If instead she screamed it, oy... If I can only offer one useful idea after many long-distance relationships and two years of marriage: don't simply close down. Explain to her what you experienced (that you saw "I hate you" -- she may have forgotten), how you reacted, and why this led you not to respond. Talk. She cannot read your mind nor you hers. It's hard work. It's worth learning how to do it.