Chatting and Cheating?

So I chat a lot, and often those chats tend to be very sexual, erotic, kinky, just downright naughty. I never really considered that 'cheating' on heather, but lately I'm having second thoughts. Last night I had a long, hot, steamy chat that resulted in multiple orgasms. I have never seen nor met the person I was chatting with, I don't even know what she looks like, or indeed like so many internet chats if 'she' was even a 'she'.

It was just typing, that's what I've always told myself. Typing and reading and masturbating, true - but how is that different from reading some erotic story and masturbating to that? Is it? I'm not sure any more.
the real problem came last night after Heather got home and asked what I had been doing all afternoon - not in a bad way, just typical conversation, a 'how was your day' kind of query - and I lied. Looked right at her, smiled, and lied. Said I checked email and did some laundry and watched some TiVoed episodes of The Closer.

Well, I DID check email, and I DID watch half an episode of The Closer while sitting on the couch basking in the 'afterglow' of multiple orgasms and hot cyber fantasy. But I couldn't tell her. I felt like it somehow crossed a line - that all this sexual chatting crosses a very real line in my very real relationship. I could always insulate myself before, because I have a very very strict policy of never meeting or even calling people I meet online, because of really bad past experience, so I could easily tell myself there was nothing 'real' about it. Just words on a screen, just fantasy.

I don't think that's true anymore. I don't think it ever was. I think that for two-plus hours yesterday afternoon I was cheating on my girlfriend, seriously hardcore cheating on her, and I feel really, really awful about that right now. I'm not sure what's changed, but something has. Something has shifted my perceptions or something.

So what do you think? Are you in a relationship? What if your partner was sitting at home having a long, steamy, erotic chat with someone on the computer, having multiple orgasms? He or she would never plan on meeting this chat partner physically, not even call them on the phone - it's just chat on the computer. Would that matter to you? If you could see them, from some hidden room, watch them type and get naked and stick a dildo in or finger themselves or jerk off, would it feel any less like betrayal than if you were watching them make love to a person physically? Is it different? Is it less wrong just because it's easier?

I love my girlfriend. I hope some day the laws in this nation would be progressive enough to allow her to become my wife. I know what I'm doing is wrong. I guess I always did. So why is it bothering me so much now?