Personally, I don't think that's possible. It's a harsh reality to face. We can pretend to be the worst version of ourselves and push others away as much as we would like, but unless we do that for years in advance, it will not change the way our friends feel when we decide to carry out our plans. You could push people away months in advance and when you finally end it and they get the news, they will understand exactly why you were acting how you were acting toward them before. The image of you in their head will not change. If anything, it will only be renewed.
We have to be okay with hurting others if we are serious about our plans to ctb. It's inevitable, and I think that's only fair. In my opinion, there is very little we can do to cushion the blow of loss in their lives. They are humans who feel just like we do, so it's going to hurt them no matter what you do. Even if they understand why you choose to ctb and support you in that decision, it's still going to hurt them to some degree. I know it's not something that any of us want to hear but it's true in most cases. People that care for us will not view us how we see ourselves, they see and hold onto the best in us.