Coping as a Coparent

Lately I have found myself wondering about what role I have in my family now that summer is in full swing and their mother is behaving rationally. Am I a placeholder? Am I the mom that the kids needed but only when their mother is acting like a lunatic? Is there room in someone's life for two moms or two dads? Will I ever feel differently about my role? Will I always just be an extension of their Daddy?

I have really considered all aspects of this co-parenting situation. I have tried to befriend and mediate, I switched to expecting reciprocity, I have stopped beating around the bush, I have been honest and straightforward... but it has not gotten me anywhere in improving the situation with my fiance's ex wife. My fiance says that it is because she never actually changes, she just goes dormant for a little while. The thing is no matter how much I think he is right, I still don't know how to handle things. For the last month I have minimized contact but it only seems to make her more hellbent on knowing things about my life.

She asks the kids weird questions about me, reads the kids texts with me, she stalks me on social media, she tried to dominate an entire day of our recent vacation with the kids trying to get in touch with her but her being unavailable. Then she pretends like things are not like this.  I tell myself that she is only controlling my feelings if I let her but how do I separate myself from that? I have considered things as extreme as being a spinster and I have no real answer. At all. And worse than that, like everything else in my family I know deep down that it is not really about me it is about her ex husband being happier without her. She doesn't really care about me, she cares about making his life less happy.

How do you survive in a life where literally nothing is about you? Is that true parenting? The kids use me to fill in gaps from their birth mother, their mother uses me to try and create an unsavory situation for her ex. Even in my own home I look around and see how I created spaces that were not really about me. Made by me to suite my family.

I can relinquish control of what goes on when they are not with me even though I miss them fiercely. I can consider that this may not be the family that I dreamed of but it is mine.

I just wonder if this is all there ever is. Do other parents feel like I do? Will I look back and regret it if I don't have more children? If they kids relationship with their mother improves to a certain point will they not need or want me anymore? Will I regret everything?