I'm really sorry to be the bearer of bad news, but...
Having just had way too close a brush with a sheriff's deputy doing a welfare check on me, during which I took the time to ask questions "about a book I'm writing" (flirting with disaster, I know), I can pretty much promise you that there will be an autopsy that, at a minimum, includes a toxicology panel. Which means whatever you ingest will be revealed, and there is no conceivable way anyone will fail to see it as suicide. Maybe back in the good old days, when you could get a prescription for N as a sleeping pill (that's how my aunt ctb), it might be classified as an accidental drug overdose, but unless you're already on the right sort of prescription meds to ctb simply by o.d.ing on them, the deliberate effort will be noticed.
So assuming that your need to ctb overcomes your (quite kind) aversion to causing your family distress, there are non-violent ways out.
Just to state the obvious, Nembutol is the Holy Grail, but can be challenging to get hold of.
I'm pain-averse, and I don't want to leave my family with the trauma of me having shot myself, so I'm planning to use an exit bag/nitrogen.
The "night night" method has recently been detailed here, and sounds like it might fit your requirements.
Hopefully others more knowledgeable than me will be along shortly.