Choking up over trying to speak about a very personal and deeply painful subject like that is NOT stupid. If there's anything in the world it makes sense to get emotional about, it's these very strong and challenging to deal with emotions.
As far as being up front about what you are wanting to do, there will never be any easy way to do that. If you have conviction that it is something you need to talk with him about, you just have to go for it. I think if in the moment you keep struggling to say it, it may be a good idea to preplan more specifically what you want to say. If you don't have any idea and are worried about rambling and not communicating what you are going through well, it will just lead you to faltering on telling him again.
So, more specifically, maybe write down the main different ideas you want to get out when you drop the suicide word and plan for the order of bringing those up. So maybe in your case, that would look like:
1. I've been wanting to kill myself, and plan to in the near future with the way I've been feeling.
2. I've been wanting to do this for a long time.
3. I didn't tell you before because I was worried about you getting upset or angry and I didn't think I could deal with that.
4. I'm still worried about how you'll react now but you matter to me so I thought you deserved to know.
5. You love him and you're sorry you couldn't find the words sooner.
Then just go through them as naturally as you can. If it helps to just prewrite a speech.
If you think it's still too daunting and you might cave again on not telling him, though…have you considered writing it out instead? Sort of like a reverse suicide note. Write about everything I mentioned above, as well as any specific reasons from what's going on in your life that make you want to do it. End it by making it clear you haven't done anything yet and will talk to him about it later. Then leave it where you know he will find it to read one of the days when you leave home. This takes the pressure off you of trying to say it in person, and also gives him space to process his own feelings about it. From what you said about him listening to you talk about your feelings, it sounds like he does care, so I'm sure it will be impactful for him. Then when you get home and he's had his chance to process it, the cat will be out of the bag and you can discuss things honestly from there, without the pressure of the in-person reveal in the way.
I'm not sure if any of that will be helpful or not, but they feel to me like solid options in your situation potentially. If any of that seems useful, or just if you want to talk more in general, let me know. Happy to support the best I can. Thinking about you and wishing you luck with whatever you choose.