I'll give you my honest opinion.
My family knows I'm suicidal. However, they're perhaps under the impression that I won't act on it.
Now, what do we exactly seek by telling our loved ones about our desire to CTB? Do we expect them to say "yah, sure, go for it!"?
I feel like you're not sure about what direction you want to go with. You fear that your bf might leave you but at the same time you plan to CTB. If you die, then you leave your bf behind too. Fear of abandonment while also planning to leave this world doesn't make sense to me.
I personally made it clear to my family that I'm suicidal cus I don't want them to be surprised, and they know very well why I want to end my life.
If your bf is loving, even if he is different that normal people, I doubt he will be comfortable hearing his beloved gf is planning suicide. I personally wouldn't feel comfortable even though I believe that suicide can be logical.
I avoid talking about this topic with my family anymore. It's indeed like you said, it only burden others. It's a different story to talk about it here since we all, relatively speaking, are on the same boat.
If the purpose of saying this to your bf is venting, then I recommend a therapist. A therapist won't solve your financial problems, but it will provide you a safe place to vent and "maybe" be able to tackle some of the trauma you have if any.
No matter how much people love us, talking about suicide with them will 100% affect their mood negatively.
Although my family knows I'm suicidal, they don't know that I've a plan. I'll never tell them that.
Also, if you think about it, there is really nothing to gain from telling our loved ones such things. My family can't solve my issues, and perhaps your bf can't solve your issues either, so what exactly do we achieve by telling them? We basically burden them and achieve literally nothing positive in return.
Mot people will just tell you to seek professional help, not that it will solve your problems, but rather cus people don't know how to solve your problems either.
I was thinking about this topic actually when I saw your post and so my reply is kinda aimed at myself more than you

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