my point is that I have no responsibility to that partner so why would I care?.
I appreciate emotions are still very raw for you, caorunn - and I can relate to how you feel only too well.
What I didn't factor in, and I wish I had done so sooner in retrospect, was the contradictory messages that I was sending to my DD.
I expect DD to treat other people with respect and consideration; it is a basic value of mine - be that strangers in the street, friends, teachers, family members - no matter who they are and what her opinion of them is, they all deserve to be treated, within context, in the same way as she would like to be treated. And I hold her to that.
And yet, I was modelling something very different. By not caring about the impact that my co-parenting was having on DDs stepmum, and by disregarding her existence in DDs (and indirectly, my) life, I was failing to live up to the standards I place on DD.
DD wasn't fooled by my apparent disinterest, either. She was old enough to understand that when a relationship ends, there are hurt feelings and broken hearts. So my attempts to ignore the existence of her stepmum only added to her confusion - she knew that it did matter to me, so why was I pretending it didn't? I'm surprised she didn't quote the MN adage to me did you mean to be so rude?. DDs stepmum is an important person in DDs life; ignoring and failing to consider her undermined my DDs trust in her own judgement, embarrassed her, and left her hurt by my hypocrisy.
I know that right now, you're not in place where you can hear this. Neither was I. But when I began to emerge from the fog, and question the justification for my own behaviour, I remembered what others has told me when I was where you are now. One day, I hope, you may remember this thread, and be in a place where you can consider it more objectively.