You can definatly have a meaningful relationship with someone online. That's how I met my husband. While I was still married to my 1st hubby... We were just friends, of course, and he was a great help when I was going through my seperation.. a cyber shoulder to cry on. He was so understanding. He listened. He understood. He was everything my 1st husband wasn't.
Would I still be married to first hubby if I hadn't met someone? No, but it would have been a lot harder to leave without the emotional support I recieved from my online friend. (we really were "just friends" until after the seperation, we didn't even meet face to face until two months after I left)
My recomendation would be to be cautious, ask her not to write anything that she wouldn't be comfortable with you reading.. or saying, for that matter.
Misty
PS.. the straw that broke the camels back with my ex was the relationship he had with someone online, ironicly, but he had taken it way too far past the "just friends" stage. The graphic sexual nature of their "conversations" was more than I could take.