This seems really odd to me as well. Particularly because you were the one saying you didn't want to leave your son.

I can see how it wouldn't be helpful if you were saying something like, "No one would care if I died" and your T had said you'd ruin your son's life, almost like if he were trying to guilt you into staying alive (I can see how that would make me feel, at least, if my T said something like that about my daughter). But I'm not sure what purpose it serves to say the opposite? Sure, if you were dying of cancer and filled with guilt, I could see a T saying that your family would be OK. But for something like this? What if it made you think, "You know what, you're right, so I'm going to go ahead and end it."

I would definitely ask him about it. Maybe he had some other reason for saying it?

I'm glad you were able to come out of the crisis (I was there myself many years ago).