Goo advice please

[Floppywillow]

I do not know where to start. I have been with my partner for 8 years and we both have children. Mine are grown with families of their own while he has a young son and adult daughter. His son is lovely but his daughter is very manipulative. She has recently applied to universities for completing her masters without having saved any money knowing her father will probably pay although he says he is not going to. The bill will be about £70:000. This is obvious as she is now contacting him all the time and usually he hardly hears from her during the year. When they do meet he is like her little lap dog. I find is so difficult especially as his son is desperate for his father's attention and rarely receives it. They do have different mothers and sometimes I wonder if he runs when she clicks through guilt. I am just exasperated and annoyed. Am I being mean?