My ex-husband has re-married, and I'm happy for him. I must admit, that if he and his new wife had had a child, it would have been very painful for me--because I've never been able to have any.
All that to say, I think it's natural, really. I'm sorry for the pain you are feeling, the grief you are re-experiencing. Please take good care and know that in time, the pain will lessen!
The ordinary acts we practice every day at home
are of more importance to the soul than their simplicity might suggest.
~ St. Thomas More