We were together for three years, but you didn’t know I existed. In fact, it was ultimately why we broke up.

At first, I understood. I came into the picture soon after your son left a long relationship. He had a young child. He wanted to try to keep everything under control to bring your grandson up in a civil relationship – adding a new girlfriend into the mix was too much to handle. I get that. I stood aside and let him get on with trying to sort it all out. I sacrificed a lot for his sake and for the sake of his family life. I put my own feelings aside, no matter how much it hurt.

Your other children knew about me, as did his friends and his ex-wife, although I suspect she ignored my existence. To any outsider, they led the perfect family life. I was there on the outside attempting to cope with the fact that I felt like a mistress. I told him all this and arguments ensued – he said he understood, but he didn’t really. His son was more important to him than anything. I held my head high and looked ahead. I thought it would get easier.

I spent days and nights wondering how you could have brought up a son who kept his girlfriend a secret

What I didn’t understand was how a family unit could be so full of lies and deception. All my family knew about my new boyfriend. He met my parents; they were suspicious that he seemed to lead two separate lives. They didn’t like what he was doing, so I started telling them I’d met you – I started lying to my own family, as he was lying to you. To protect him.

I couldn’t understand how you were so blind to him leading another life. I wanted you to reprimand him for what he was doing to me, to pull him up for leading a double life. I spent days and nights wondering who you were, how you could have brought up a son who kept his girlfriend a secret. I hated you for it. I hated you for not realising I existed, for not creating a comfortable environment in which he could be honest. I spent a lot of time daydreaming of meeting you and feeling a part of the family.

I thought that, if I met you, I would feel better about our relationship, that I wouldn’t feel as much of an outsider. But he didn’t budge, no matter how much I pleaded. He said it would dramatically change the relationship he had with you, his ex and his child if you met me, the new woman in his life.

But he had left his wife. So, as the years went by, and as patient as I was, it seemed like he would never let me be a part of his life. He was having his cake and eating it, too. So, I left.

I loved your son. I still love him. Maybe we were both naive. Maybe he never even loved me. Maybe I was a fool and shouldn’t have put up with it for so long. Despite all the confusion, arguments, distress, hate and upset, we loved each other.

It has taught me to go into my next relationship with open eyes, it has taught me life lessons: how much I can handle and how strong I can be. I still hurt from it all and I still love your son. I just hope he doesn’t treat his next girlfriend like he did me. For three years, I yearned to meet you – begged to meet you.

Now, I suppose I never will.

Anonymous

We’d love to hear your stories

• We will pay £25 for every Letter to (please write about 600-700 words), Playlist, Snapshot or We Love to Eat we publish. Write to Family Life, The Guardian, Kings Place, 90 York Way, London N1 9GU or email family@theguardian.com. Please include your address and phone number. We are only able to reply to those whose contributions we are going to use