Georgina Hobbs-Meyer discovered her husband had had cyber sex. Now she has two warnings for users of social networking sites: your whole life can be exposed - and don't get dumped online

My mother emailed me last week to tell me she had joined Facebook. We don't chat on the phone; we email. Soon I expect she will want to poke me, write on my wall and, worse still, tag me in photographs of my wedding last May. Well, not if I can help it, mama. I love you too much to expose you to my online self.

You see, she doesn't yet know that I, her 24-year-old daughter, am about to divorce. She can't see my Facebook status, so why would she?

Mummy, how do I tell you I'm a Facebook divorcee? That the son-in-law you try so hard to like cheated on your only daughter using the social networking site you so adore? That your daughter learnt of her imminent divorce via Google Mail's free chatting facility, Gchat?

Prince Harry may know how I feel. Would he even have known that he was single again if Chelsy Davy hadn't flagged it up on Facebook? Her recently changed status cascaded through her friends' newsfeeds to inform all that she was no longer in a relationship. Snap went the trademark red heart, sending gossip rocketing offline and on to the printing presses, neatly bypassing Clarence House. Headline: "Chelsy Davy: A change of heart on Facebook."

Oh Prince Harry, yours is a state I know too well. You, me, all of us, we're helpless to defend ourselves once our partners rush to Facebook our misery over a thousand flickering screens. The sad truth is that, once you announce your relationship on Facebook, and for as long as you are linked to one another by html, your status – hell, your love life – is on show to all. Even though I've opted to delete my relationship status rather than modify it Chelsy-style (she, like my husband, distastefully rushed to invite comment on fresh singledom), people will see the photographs of my wedding and draw obvious conclusions.

Not that many people take relationship statuses to heart. Even if they should, they do not read "X is married to Y" and immediately write off the object of their affection as unobtainable. My divorce is proof of that.

It began with a woman he met at a party. But it was within the sticky web of Facebook where they really got to know each other, despite the photos of us and our "married to..." status. I know this because my husband once logged on to Facebook and foolishly left the room. I began to use his Mac, only to find myself blasted into the middle of a sizzling cyber romance.

And once I was in, I was hooked. Their lusty emails touched on bad Beat poetry, but were infused with textspeak, their coy cyberflirts rife with emoticons. It felt like I was stuck in a hyper-reality where Douglas Coupland wrote Danielle Steel novels. "Could this really be happening six months into my marriage?" I wanted to comment on my own Facebook wall.

And whatever Facebook was before that – a relatively innocuous way to keep up with friends, I suppose – it has since taken on a more demonic intent.

Most infuriating is my near-constant Facebook-style method of internal communication that I cannot switch off. Whenever I do something, I narrate internally. Something like: "Georgie is hacking into her husband's Facebook account just to see if she knows the password... Georgie is pleased she knows the password!... Georgie is disturbed to find her husband chatting to a very pretty 19-year-old rather a lot... Georgie is furthermore disturbed to discover her husband is partaking in cybersex with said 19-year-old!... Georgie is slowly realising that while she has been Facebook-chatting with her husband, he has simultaneously been sending the 19-year-old dirty messages!!... Georgie is considering divorce." That's pretty much how it went.

Actually, I didn't get round to asking for a divorce. Pathetically, I did feel somewhat vindicated when my husband, once caught, deleted the 19-year-old at my request. And what did her status read? "Someone deleted me! I know who you are!" Scary stuff.

So, divorce. I don't know anything about getting a divorce after you have caught your husband having real sex, let alone text sex. If a poke is slang for fornication in real life, but polite in social networking terms, where do I stand?

Instead, I asked him to fly back to his home country so we could take a break from one another. I still wasn't sure how fatal a crime two-timing online was – me and her duped by the same typist; sex with me in the marital bed, sex with her via keyboard.

I received a curt Facebook message from him a few months later asking to "book some Skype time". This was serious. Skype, the videophone software that allows you to talk face to face to anyone in the world with an internet connection, was not used lightly between us. When we courted but lived in different countries, it was through Skype that we would have our most intimate conversations, eye to eye. Almost.

Playing cool, I demurred: "Just email your concerns." But before he'd got a chance, we found ourselves on Google chat. Here is a transcript of the conversation: Me: "why cant u just email some of what u want to chat via skype?"

He: "i think we need to get divorced, and move on from this point in our life, I still love you, but our marriage has failed and needs to be over."

The typing is appalling – but not unusually so. It's also inaccurate. The marriage didn't fail. It's just that he couldn't resist typing things that he thought would have no consequence in the flesh and blood world. But no longer. The two worlds are on a collision course. The question is, which will take precedence – the Facebook hyperbole where all and nothing can be summed up with a "?" and a "!", a world where self-promotion cuts out the middle man and you're the last to know if your own daughter is married? Looks like it.

I know divorce was never nice, but wasn't there a time when communication, on the whole, was romantic? Painfully slow, granted, but perhaps a chance to reflect is what we need. Where once it was smoke signals across the American plains, homing pigeons over chimney tops or calling cards plucked from silver trays, we now have the puerile, typically misspelt, Facebook status update. With all the charm of an overbearing town crier on a caffeine overload, the monster of Facebook feeds off our ids, leaving us bored office workers and near-royalty wrecked after a day of reading between the comments.

Now single and unable to delete my husband from my list of friends (I am paralysed every time I try), I'm acutely aware that he can see my every move, just as I can see his. Foolishly, I fiddled with my settings and ramped up the amount of information I am fed about him. When he adds a friend or pretentiously quotes the vacuous Bret Easton Ellis in his status updates, it makes me want to vomit. And still I ramp it up.

This perverse circumstance has seen me go the way of the online bunny-boiler. I've added more friends than I care to mention just to infuriate him. I've got buddies I've never met in New York and Australia, a Canadian spammer who believes that raw food cures cancer and – worst of all – people I dislike in real life. I even tried adding Chelsy Davy since, from hard-nosed appearances at least, she's doing pretty well.

The pursuit of letting endless idiots become my friends is draining. Having to then show off about it with a wall comment, more so. "Georgie is wondering what is happening to her, her friends and the man she married? Txt bak!"

No, Facebook is not for you, mother; it is for the bored, the boring, the unfulfilled. Install it on your BlackBerry or iPhone at will (my husband just did), but don't let it fool you. Just because you're mobile and telling us about it doesn't mean you're going anywhere interesting fast.