Mallory,

Here’s what I would try: Lay your hand gently on his arm, or take his hand. If he doesn’t look at you and make eye contact, give him a very gentle squeeze or caress. When you have his attention, smile and with as much love as you can say something like, “I’m sorry, but this topic is a little overwhelming for me right now. Would you mind if we discussed something else?” or maybe, “I’m afraid I haven’t had quite enough coffee yet to absorb what you’re saying. Can we please table this until later?” Especially now that you’ve already discussed this topic with him, I’m sure he’ll respect your request and by shifting the focus of your request from “You’re too verbose” to “I’m just not feeling up to it” he hopefully won’t take it personally.
Hugs to you. 🙂