I had been part of my stepdaughters life since she was 2. We split when she was 11. Within a week he introduced her to the woman he was having an affair with and told her to lie to me about it.
It has been HARD. I retained partial custody of her one night a fortnight on her dad's time (will full consent of her mum who I get on well with) and in the first few years i still took her on holiday with me and her brothers (my bio kids).
Last october (so 3 years post divorce) ex husband told me she didnt want to stay at mine any more. I believe it was his manipulation but shes very much a daddy's girl. She never actually told me she didnt want to come, he did.
Shes useless on her phone so I would text and get no reply. I was told she wants a relationship with me but one on one not with my kids there. Which is more than my own kids get and was essentially ex husband trying to control me because the only time my kids aren't here im with my partner so would miss time with him for stepdaughter.
It felt very much like I was a parent when there was something that needed paying for that her mum and dad can't afford and I can.
Its really hard. I love her as my own but she is being manipulated by ex as a mechanism of control. She is 15 now so I stay in touch by texting. I send her memes. I invite her to things if I think shes interested.
But he also put her in an impossible position by introducing the other woman so soon. Stepdaughter is lovely and kind and thinks well of everyone. I have no doubt she loves OW so felt disloyal to both of us in the end.
To answer your question, I am in touch, its hard to maintain and evolves with age. And if your ex is a dick they will make it harder than it needs to be!