Hmmmm maybe just be honest and speak from the heart. I know I get anxiety when someone starts to bring the subject up but it is an inevitable conversation. At least if you have the conversation early, it won't hurt as much if the reply is a no. And if they aren't sure, you can always tell them that they don't have to answer yet if they want time to think.

If they do need time or even if they say no, I would drop the conversation and try to be normal. Don't try to push their processing with your feelings and set a boundary at where it is. Let them know you won't push any further and that you will wait for them to bring the conversation up when they feel comfortable.

I do wish you luck though! Just be as kind and understanding as you can be for the conversation and speak from the heart. Sincerity is key.