Black-and-white thinking, or splitting is not unique to BPD alone. Many people experience splitting sometimes but people with BPD commonly experience this a majority of the time. This is definitely a characteristic of BPD but since it can occur outside of BPD as well, it would not be appropriate to say whether or not its something that could be diagnosed for you. However, the actual act of splitting can be helped by something called Dialectical Behavior Therapy, which helps in seeing that two opposite things can be true at the same time. There can be a middle ground.