It's your birthday. How strange that it is my daughter's birthday and mine, too, in the same month as yours. The three most important women in his life, we all celebrate our lives within weeks of each other. This time last year I was unaware of the affair. I know now that for your birthday he took you away to a concert and you stayed over in a hotel. He told me a very elaborate, believable lie, and when he came back he made us all laugh with the story of the night before. But in reality it had been your first night spent together. Probably quite a big anniversary in its own right.

I wonder if you felt any guilt or shame that night. Did you give any thought to me or my children? And a couple of weeks later when he and I went away for my birthday – my attempt to try to bring us closer – were you jealous? I know he contacted you while he was with me. Did he tell you how he wished he was there with you and not me? I imagine that you both already felt a sense of entitlement – even then. Before I even knew. I expect that you were both already disconnecting from the people whose lives you were about to shatter apart.

Since then you have had many nights together because he is with you now. You are free to do whatever you want without it having to be secret. I wonder how this has changed things. No longer an affair – now a relationship. Yes, you may call it that now. I wonder what you will be doing for your birthday this year. My heart is still broken, and the thought of you celebrating together is very painful for me. But even though you can do this in the open now, just know that this relationship will never be legitimate in my eyes.

So a couple of weeks after your birthday, I will turn 50. Single for the first time in 21 years. I have quite a dilemma choosing how to celebrate. If it wasn't a "big" birthday I would probably just let it pass fairly quietly. But I can't escape from the fact that if he was still here, we would be planning something grand. We had talked about a big trip this year; I had been saving up for it. All the options I consider feel like attempts to compensate for my loss and that just magnifies my sadness and loneliness. Some ideas are defiantly grandiose, and could end up feeling hollow and pointless. Either way I feel I am trying to choose based on the absence of him. I need it to be about me.

I wonder how things will be for us all in another year. I expect you are in the honeymoon period now, but maybe as the novelty wears off you may find that there is no real substance after all. Many affairs fizzle out in that way after a year or two. He had a mid-life crisis and you rescued him. I think you will resent that eventually, as you realise that he is not very resourceful emotionally. I fully expect his unresolved issues will re-emerge and play out again. He chose to hide from himself rather than facing whatever led him to betray me and detonate his life. Perhaps he will do to you what he did to me. I sincerely hope so.

You will know, if you have any insight, that he has buried his grief at losing me, and at what has happened to the relationships with his children and his family who no longer respect him. He is in denial. This too will play out in time.

So this month as we all celebrate our birthdays, I will reflect on how my life has changed; what opportunities this presents to me. I can choose how I define myself, and I approach this transformation with hope and with spirit. I am facing and enduring my grief, and will emerge stronger as a result.

This time next year on your birthday, whatever you are doing – together with him or not – my intention is that you will both matter a lot less to me. Anonymous