You're talking about the "Bus envelope".
Pick a person, a trusted loved one or family member likely to survive
you, and let them know where those written instructions are.
It's well within the remit of existing lawyers and I advise you
involve one. Wills are standard documents. If there are time-critical
actions make it a legal instrument that precedes any transfer of
responsibility to an executor (who may not end up being the trusted
party you designated and probate can drag on for years in complex
cases.
Yes it's a security risk because you'll need to write some things down
including passwords. Tell them a password in advance that they'll
never forget and anticipate that they may be in shock or unable to
follow complex time-critical instructions at the time. Use a unique
shared secret like "Remember what that bird was singing when it sat on
the balcony on our honeymoon night?"
Many people in service are required to leave a "professional will".
Clients need to be informed. Debts paid. Records destroyed (there are
many legitimate circumstances for this).
And god willing, it never happens for you.