I am no expert in this.
But it seems to me like at some point in the future you are likely to have an episode of negative behaviour.
If you have told him in advance, there is some chance that he will be able to deal with that behaviour as something temporary, not permanent. Because you have told and discussed the possibility of that behaviour in advance, there is a better chance he will be able to understand your condition and deal with it for what it is.
If you haven't told him in advance, then he will get both the
revelation of the BPD and the negative behaviour simultaneously. He himself might not be in an entirely rational state after this and may deal with it negatively himself rather than calmly if he has time to understand the condition in advance and prepare for it in case it happens.
Yes, I think if you tell him there is a risk he will not want to continue the relationship. But there is also a chance he will want to work with you to try to understand and overcome these issues and that is better done when you are not experiencing negative behaviour.
Maybe you should talk to your GP/counsellors and ask them what they think about the situation.
BTW, I don't think there is any right or wrong answer to your question, simply different outcomes with different consequences.