I have two kids...both under the age of 10.... I just posted about this in another thread, but I will repeat it here.
As a child, I expect to have to bury both of my parents - one day. However, as a parent, I do NOT expect to have to bury either of my children.
If either of my children committed suicide - I would be permanently devastated! Even though I have made the decision to CTB myself (hopefully not until they are much older) it would still leave me devastated, filled with grief and anger and sadness, confused....and most likely totally consumed with guilt. I would absolutely blame myself. I would go crazy trying to figure out what I should have/could have done to help. Or what I did or said that caused it...or what I could have said or done to help. Or how I couldn't have seen it coming. Why they didn't feel comfortable talking to me. Why they didn't come to me for help. Even though I fully understand what it feels like to be suicidal, as a parent, I would still feel like a failure.
I'm not saying any of this in an effort to change your decision. Just giving you some things to think about in terms of how they may feel....which I hope can help you ease their pain.