When sharing thoughts with people, I tend to just blurt them out with out any follow up, or give any context.?

I guess its just a bad habit, but I need to learn from my mistakes. Like for example, I was chatting with this one person, and I said "hold on just a sec". I then went on to say "I am writing a letter to my ex, so I ill be a minute" I didn't lead up with anything, I just blurted it. I realize that that is not "normal" for what ever the word is worth. What would be a good way to lead on with somethng like that? whats a good way to present it, and not have it look at as an odd way of presenting things. Maybe I over analyze, I dunno..