@Adrinaxo I had it the other way round of your situation, but I can relate to you feeling hurt.
My long standing closest friend had twins in our late 20s. We'd been best friends since uni. I gave her so much support all the way from newborn babies through toddler years into childhood. I visited frequently, helped with practical things whilst visiting, took her babies out for walks in their pram to give her a rest at home, as they got older I took them for days out, I always made sure I remembered their birthdays and bought them thoughtful birthday presents every year, and presents every Christmas, I listened to her when she was struggling with parenting and although I wasn't a parent myself I was still able to listen, care and support. I made sure I invested in her children as much as I invested in her, because I saw her DC as part of her, and I made sure to consider them and include them in every social arrangement we made together. She would ask me to babysit when she returned to work if she was stuck for childcare, and if I could I did (I worked full time so admittedly couldn't always, but if I could I did), she asked me to commit to a swimming course when they were 6 months old as she needed 2 adults for each baby and the swim course was at a time when her DH worked, so I did it with her and it was a 1 hour 30 minute round trip drive for me plus giving up my free time. But I did it because she asked and I wanted to support her. Alongside this, I also still saw her on a 1:1 basis which was instigated by her as she said it was important to her to see her friends for evenings out without her DC being there.
Fast forward 12 years, at which point I was still seeing her 12 year old twins regularly, I always made sure to chat with them and engage with them as they grew older - I had a lovely relationship with them, and I was continuing to treat them on their birthdays and at Christmas. And then I had my first baby, followed 18 months later by my second, when her DC were 12/13.
Naively, I assumed her level of interest and input to my DC would be the same as I'd given to hers. But I received zero interest from her. Nothing. No congratulations on your new baby card (I had cards from everyone else, but not her). No input. No thoughtfulness. Barely any visits at all. And on the rare occasion she did visit when they were babies, she would lecture me sternly about how I must stop picking them up to comfort them if they're crying. Then she'd tell me I had gained weight. I'll never forget saying to her "My work colleagues are texting to ask to see me and meet my baby, but I feel a bit nervous about seeing them, I don't know why it's making me feel nervous though". In hindsight, I was nervous because I was feeling fragile after a traumatic emergency birth and I was in a lot of pain post-emergency Csection infection. Her direct reply to me was "Well you do look an awful lot heavier now you know, and your colleagues will notice that, so I expect that's why you're nervous about them seeing you". Then she'd talk all about her life and then look at her watch and swiftly leave. Then she never bothered visiting them anymore.
My DC are early teens now, and in their whole lifetime they have never received one birthday card from her, nor one birthday present from her, nothing at Christmas from her, ever. Not as babies or children. My eldest vaguely remembers her if my DH makes reference to her in conversation, and my youngest has no idea who she is. Because she has literally put zero effort into ever seeing them or showing any sign of interest in them.
So although it's a different situation to yours, I really understand how you feel.
My friend's non interest in my DC really hurt my feelings after I'd been so involved in her DC, and it has really broken down my feelings towards her. I've stepped right back from her and my feelings towards her changed a lot.