People Pleaser Question

I say yes when I want to take time for myself. I say yes out of guilt to my family because I struggle with ‘thoughts’ about ‘what if’ this might be the last time I see them. I say yes every time they ask me to do anything out of guilt/obligation. They dont make me feel guilty but I feel it myself. How can I help change my thought so that I wont feel guilty for saying no to them in the future? I always think, if I say no and something does happen to them, I will feel so guilty and heartbroken. Thank you!