A young woman who thought she had everything mapped out perfectly is suddenly on her own – and the jealousy is unbearable. Mariella Frostrup says it’s hard but it’s time to look to the future

The dilemma A year ago, my partner of 12 years (fiancé of five) told me he wanted to end our relationship. We had bought a house in my dream town and just sent out wedding invitations. I found myself, aged 26, living with my parents – the beautiful future I had planned stripped away. I discovered he was seeing a woman from work. It became obvious he left me for her. I’ve had counselling and continued working, even tried dating, but I’m desperately unhappy. My future is insecure, all my peers are getting married and starting families, and I feel I will never find love again or have the family I wanted by my 30s. I’ve cut contact with lots of friends as I’m so humiliated and jealous their lives are on track. I have often thought of suicide. Meanwhile, she has replaced me in all aspects of his life: staying in the house where I stripped wallpaper until my hands bled, having dinners in the little romantic local pub. I live in fear of her getting pregnant, or them getting engaged. I think if I hear that news it will kill me. We did everything together from when we were 14 years old and life feels empty without him. I’ve thought of moving abroad to escape, but I know the pain would follow me.

Mariella replies Hold that thought. Whether you travel halfway across the world or stay put in your childhood bedroom, the pain you describe will remain your companion until you radically alter your approach. For reasons you don’t elaborate on, and maybe don’t fully understand, you have invested everything in this relationship at a point in time when there’s so much else that could and should be fulfilling and thrilling you. It’s little wonder that you are struggling to get to grips with your own destiny while you remain buried under an avalanche of paralysing self-pity. Paying so much attention to the detail of your ex’s life definitely isn’t helping. He’s in a relationship with somebody else, and while it’s a devastating blow to your confidence and you are allowed to mourn, it’s even more important that you develop the wherewithal to negotiate this setback. As you observe, everyone else is getting on with their lives – and that isn’t a personal affront, just a statement of fact.

Existing through the prism of another person is a precarious position to put yourself in. You’ve been particularly vulnerable because you’ve been together since you were children, but maintaining such a childlike dependency is no way to forge ahead into adulthood. At some point the relationship would have collapsed under the weight of such reliance and expectation. Our lovers may offer the illusion of security, but only we can make ourselves whole. Instead of shutting doors to friends and future relationships, and judging everyone else’s experiences as more favourable than your own you need to start seeing things as they really are. No one who has experienced a relationship breakdown will fail to have sympathy for what you are going through, but you seem determined to wallow in the mire. Returning to your parents may make sense in the short term, but that shouldn’t be your permanent resting place.

It’s good to have a dream, but it needs to be an infinitely adaptable one. Perfect homes in dream towns, fairytale weddings, relationships that endure from cradle to grave – these are all Disney tropes, not real-world certainties. And how tedious, anyway, to be trapped in a universe where everything was mapped out.

While it might appear that your friends are leading the charmed life that should be yours, if you showed an interest in them rather than cutting them off you’d discover that they, too, have difficulties to surmount. I know your emotional experience feels singular but it’s as universal as they come. Love makes the world go round and also stops it in its tracks. Learning to navigate rough seas is one of the most essential skills you can acquire, but if you continue to think about suicide you should seek professional help (the Samaritans are on 116 123).

Heartbreak is not an incurable disease, it’s an emotional state. We can allow our emotions to override our judgment and hurt to become a form of self-harm, but it’s a toxic way to conduct our lives. Far better that we learn to surf the biggest waves of pain and emerge stronger, wiser and better prepared for the next hurdle. Your destiny, like your relationships, is something fluid, evolving and unpredictable.

You wanted to settle down and have a family by 30, an admirable ambition that you could easily still achieve if you were prepared to countenance an updated version. Instead, you are holed up in a miserable world of your own making allowing unrealised plans to rule your future rather than help you make better choices. You can rant and rave about betrayal and allow every detail of this man’s new life to cut you to the core… or you can shrug your shoulders, look at the many millions much worse off and appreciate that suffering is merely our groundwork for joy.

Happy days are definitely over the horizon, but you have to make those first steps towards them on your own.

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