Maybe I'm a nutcase, but I've taken the time to prepare a set of scenarios under which I would no longer want to live, and think about what would need to be taken care of to exit the world without undue burden on those that depend on me. That seems like an eminently rational thing to do.
I believe professionals would categorize what you wrote there as "planning suicide". So long as you have not started "taking care of" those things you have not begun executing your plan. Planning is a rather big step beyond contemplating - I hope you're doing better now. You may also want to consider that actually getting your affairs in order could be an enabler.
It's evaluating a set of contingencies. Like, the general staffs of armies make war plans that they will never execute, unless the particular parameters fall in place, all the time. To do otherwise would be irresponsible.
The public health responses to you should be very different to the people who experience rapid onset despair.
When I was a kid my oldest brother enrolled in some free counseling from a church. They had him fill out why he was going to counseling so he honestly wrote down that he had been having suicidal thoughts.
So this church freaked out and sent a pastor and someone else over to force him to promise not to kill himself.
Which as you can imagine was horrible and completely broke his trust in the system.
Also taught me to never ever be honest with people about serious things like suicide unless you've already know how they will react or you think you are a real danger to yourself.
Suicidal thoughts from time to time are fine. The issue is when you start to have real intent to carry them out. That's when you need help.
My sister attempted suicide as a teenager and the police that responded spent hours ransacking our home and further tormenting my family for no good reason. Then to think of her being locked up in the hospital (I wasn't able to see her for at least a week).
If I were having such thoughts, I certainly wouldn't tell anyone for this precise reason.