As hard as it is, don't mention love yet. Tell her you're thinking about her often, wondering if she's ok, remembering how happy you've made each other and that you'll be writing periodically to make sure she's ok and to make sure she knows she can count on you no matter what. Trust me--easier said than done! That's why I'm "cantstopcrying"! Honestly, though, it may be better to use words like, "care deeply", "you're in my thoughts" "holding you in my heart", words that convey love without the pressure-filled word.