Or something like that, anyway.
Reading–or trying to read–a story where someone has gone through and stripped out all of the ellipses and replaced them with a single period is almost enough to make me tear out my hair. They didn’t bother replacing them with em-dashes, or evaluating each ellipse on a case-by-case basis to see if they actually needed it to stay, they just removed them wholesale. (Or maybe they were never there in the first place, I don’t know.)
“I.” isn’t a sentence. It should not have a full stop at the end. “I…” or “I–” conveys a sense of being uncertain and interrupted, respectively, if that’s what you’re intending. If you want your reader to take a little break, you can start with “I,” add some narrative, then go back to dialogue.
Seriously, there’s a really good reason that style manuals are intended for everything except dialogue: people never ever speak exactly like a style manual was the only book in the house during their formative years. Not even the most rigidly proper speaker of a language does. Not even people who are paid professional editors.