The dilemma My (now ex) best friend and I work for the same organisation. In September she resigned, but I got a new senior position so offered her a role on my team, which she accepted. From day one she came in late, was texting all the time, didn’t do any work and was rude. Over time she became more abusive – belittling and undermining me. She even stole a gift from my boss and re-gifted it to someone else. I’ve tried to coach her to understand the issue, but with no joy. Now she’s leaving and threatening to reveal our WhatsApp messages – moaning about our firm and our leader, like friends who work together often do. I feel held to ransom. I honestly believed that those messages were off limits. I’m worried they will ruin my career.

Mariella replies Off-limits? There’s a quaint 20th-century idea! As a senior employee at a big company you should know better than most how much of our private lives are on the menu for public consumption these days. So little of our existence remains our personal domain and even more terrifying is the knowledge that we are passively strolling towards ever greater exposure.

Every time a company whose wares I’ve perused online starts stalking me with unsolicited enticements, I get a cold shiver down my spine. Not enough to curtail my internet shopping… it’s far too enticing a displacement activity to reject it outright. But at such moments I do fleetingly consider lowering my exposure.

Once you’ve launched your secrets online, it’s only time that stands between you and their revelation

It doesn’t matter whether your secrets are career threatening or minor indiscretions, once you’ve launched them on to the web it’s only time that stands between you and their revelation. As soon as you’ve availed yourself of one of the multitude of communications systems open to you with a quick click you might as well be standing on a soapbox with a loudhailer. At least on a soap box you’re merely revealing what you choose to. With online activity, for the giant corporations joining up the dots of our daily activity, we’re offering full-frontal nudity on our daily lives. The question is no longer if other people will get to see your thoughts, but who and when. Yet we merrily carry on exposing our most intimate feelings, our family photos, our grocery choices and our social experiences.

I appreciate a sermon about internet discretion is not what you wrote to me for, but when it comes to the souring of your friendship I have less material to work with. The smattering of “corporate” speak in your email, saying for example that you tried “to coach” your friend, makes me wonder if the story is as one-sided as you tell it. Either she’s a wholly ungrateful wildcat who needs to be restrained for her own safety, or you and she have embarked on a complex power struggle from which neither looks likely to emerge the victor.

From what you tell me, she’s at the stage of last resort, which is where the threat of exposing your private messaging comes from. Can you be entirely exonerated for driving her to this point? I only have your version of events and from that vantage point her behaviour is unforgiveable. If that’s the whole truth then all you need to do is work on thickening your hide, brazening out the text chain and getting on with the job in hand. I suspect your employer would find it very difficult to fire you for a series of messages, though they might call into question your judgment. There may well be privacy considerations you could lawfully raise, but personally I wouldn’t go that route. Instead I’d accept I’d made some poor choices professionally in allowing this woman to take advantage of my friendship to dodge her responsibilities at work.

I’m not sure how long you’ve left her to idle around the office, showing her disdain for the chances you’ve proffered, but I suspect it’s way too long. Now you tell me she wants to leave and the best advice I can offer is to embrace the opportunity to see the back of her, gird yourself for the discomfort of your chats being exposed, and learn from your mistakes. It’s a fine thing to offer a friend an opportunity, but it can so easily become complicated. I’d try hard to turn the other cheek, be gracious as she departs, shrug off her threats to share your office gossip chain and tread more carefully in future.

She sounds like she wants to punish you, for reasons I don’t understand, but the surest way to draw this sorry passage to a close is to not allow her to get under your skin. Your personal messages, even in this wide-open world, are not your firm’s concern and if you’ve been indiscreet then simply laugh it off as the irrelevance it really is. Once upon a time those conversations would have begun and ended in the bar. We have only ourselves to blame if we offer them up in a format that haunts us forever.

If you have a dilemma, send a brief email to mariella.frostrup@observer.co.uk. Follow her on Twitter @mariellaf1