A disciplined response is harder to manipulate than an emotional one.

An emotional response is easy to produce and therefore easy to steer, which is why people who want something from you will often go for the feeling first. A response that runs on principles decided in advance does not depend on your state at the time, so provoking you does not change the outcome. This does not require being cold. It requires having decided some things before the pressure arrives.

Decide your terms in advance for the situations that recur: what you will accept, what you will not, and how long you will wait before answering. Then apply them regardless of how the conversation feels. Consistency is the thing that cannot be manipulated.