While I can understand your desire for open communication, 14 is still a child. He is way too young for this kind of conversation, especially when it concerns his own parent, who he no doubt loves deeply. I have a son around your son's age, and I would only even consider talking about this subject with him if he was an adult.
As parents it's our number one job to protect our children, and it would be placing a huge burden on him to inform him of this. He'd likely be shocked and upset to hear someone he loves talking about their own death, yet he wouldn't be able to process those feelings with anyone. He wouldn't be able to talk to his other parent, other family members, friends, or anyone else about his feelings. Additionally, with the overwhelming societal attitude being that CTB is only a bad, terrible thing that can't be a rational choice, he would likely feel that it's his responsibility to somehow "help" you or tell someone who will "help" you, and if you told him he can't share this with anyone, he would feel incredibly conflicted.
I very much understand wishing you could share your true thoughts with the people in your life, and I know how isolating this is. But this is an adult topic that involves moral issues that are too advanced and heavy for a child.