You experiencing it as a major misstep is what really matters here, I think. Why he said it, what he really meant, the impact of suicide on others, and so on are sort of side issues. He might be able to explain his comment and it might make sense to him, he might have meant it with all best intention and care, but the fact is that you experienced it as a time of major misattunement when you were desperate for connection and contact because you were adrift. For me, that is what I would explore with him (what was that like for you, is that a common experience for you, etc) rather than the content of his comment.

For the record, I think it was a stupid thing for him to say.