There is absolutely no reason for apologising. You should never plan to ctb if you are not one hundred percent sure that this is the only way for you to go.
Reading your text, I somehow got the feeling that you experience a distinction between people having decided to ctb and those who don't, with the first ones being "right" or "better" than the latter in this forum. This is an extremely dangerous way of thinking and I'm certain the overwhelming majority of all users would agree with me when I say that this is absolutely not true. Why should it be that way?
Both the reasons why somebody decides to end their life and the decision itself are extremely individual.
I can understand that you are afraid of failing your attempt, this is reasonable and important to consider. There is no "safe" way to ctb and it is harder to ctb than it is mostly depicted.
If you don't think that this is the right time to end your life, don't do it. You will always have the possibility in the future.
I don't know your background, but I am sorry to hear that you suffer that much.
Being in that state of mind, I know how hard it is to see another way out. Still, as long as you are not certain that ctbing is your only way to go, I highly encourage you to try anything that might help to lessen your pain a bit. I wish you all the best!