I try to always look at whether or not I will matter in 500 to 1000 years and it's very unlikely I will. I know that pyramids and great buildings exist but can we find a peasant from 500 years ago and care whether or not they committed suicide?
Do things have to matter in 500-1000 years in order to matter? Nothing is permanent, even the great buildings (look at the Twin Towers or the ancient city of Palmyra). Mattering is relative and in order to believe that we matter outside ourselves and each other we'd have to believe in a Deity or spiritual order of some kind. Unfortunately I don't.
I'm sure you matter to your kids. I'm sure it matters to them, and will matter, that you are in their lives as they grow, go through adversities and happinesses, have kids of their own. If you go they will be devastated. What if they become affected by mental illness and suicidality? You need to be here for them. You matter not because you matter in 500 years but because you matter to those around you, here and now.
I'm not being preachy and I'm in no place to. If it wasn't for my own miscalculation I would have CTB'd by now, and done this to my kids. In my case it wasn't because I didn't think life mattered, but because I'd created a narrative that they would be better off without me. I now believe that was false and - in my case - lacking courage. So I accept that life will be lived with CTB on my shoulder and mental illness in my mind, but try to make the here and now have meaning.