AITK for choosing my daughter's delivery over my ill BF's nurse duties?

I have been “dating” a man for close to 15 years. We are both widowed. I had 2 teenagers at the time and his 2 were already grown. We have never lived together. In fact his children told him that did not want him to get remarried (assuming because he is well off) but I am comfortable on my own and put two kids through college, own by home free and clear and now happily retired. We travel but I wouldn’t say excessive money is spent. We are companions and he is a great guy.

Now, recently my daughter is about to have a baby and she is out of state and I plan on staying with her for 3 months. My BF is having open heart surgery and his kids want me to stay home to take care of him because they both work and I told them I cannot.

Now, they are mad at me because I won’t be available to be their dad's nurse. He has plenty of money to hire a caretaker. His kids don’t want that in case there are complications he would want me there. AITAH for standing my ground and leaving to be with my daughter and first grand baby?

Source: https://x.com/MrPitbull07/status/2016058318394183829