I used to have a good relationship with author A, but now it's broken. However, my work is heavily based on the work of that author, and I'm not sure if citing it without informing them is OK here. Would there be any potential trouble from this? What if they explicitly tell me to not cite theirs?

I used to have a good relationship with an author, but now it's broken. However, my work is heavily based on the work of that author, and I'm not sure if citing it without informing them is OK here. Would there be any potential trouble from this? What if they explicitly tell me to not cite theirs? I just don't want to make the relationship worse, because they may not want to have any affiliation with me. But this is just my thought, I really don't know what they really think.