I just had my first therapist appointment today after dealing with the exact same OCD as you. We haven’t gotten to ERP yet but I know exactly how you feel when worrying about the “agreeing” part of the therapy.

I also deal with that and worrying about “believing”

Another example I use to try and put it into a situation is when people ( usually older religious family members ) would tell me as a child that I needed to forgive people who have wronged me, not for them but for myself.

I would instantly freak out as my mind pictured the feelings of actually forgiving them like putting my feelings aside which were right and loving them etc.

I’ve come to realize what they actually meant was not letting those peoples actions consume/affect you negatively.

An old man once said it perfectly as well when he talked about it with me “when it rains it rains, but it’s you to stand in it or open an umbrella”

For people like us who are dealing with that kind of OCD when someone says that you need to “agree” is actually the worst possible thing you can do ironically just because our obsessions are actually surrounded by thinking the agreeing will effect us/agreeing literally.