YOU CAN NEVER GO BACK ON WHAT YOU SAID. Once you've said something and it's out and it's been heard, the damage is done, there is never any way to take it back. The only thing you can do is try to mend things and make it better. In your case, the damage is not done and you can in a way go back on what you said. Just next time you're having a lovey dovey conversation, or something. Or when you're all cuddled up and kissing, just tell him you love him and want to be with him the rest of your life and have a family, etc. And if he asks about the other night, just apologize, say I'm sorry and that you were scared you thought the talk about your future would be too soon and might have freaked him out. You'll be fine. If he's a good guy it won't be that big of a deal.

LOL! Wow fatalistic huh? You can always go back on what you said. Just go umm remember the other day when...Yeah I didnt mean that.

There ya go!

Depends, doesn't always work. "You suck at sex." How do you take that back?

Once the words come out of your mouth and are spoken it's a done deal; you can't take them back. All you can do is apologize and say something like "I've been thinking about something I said the other day. I realized that HOW I said it came out all the wrong way and I'm sorry." Admit that you sometimes speak too soon and it all comes out the wrong way. You need to reassure him how you truly feel about him and he needs to do the same toward you.

You didn't mention how old you too are so it's hard for me to comment on "I do want marriage and a family someday relatively soon".

Youd say: "umm remember the other day when I said you suck at sex?...Yeah I didnt mean that. Lets have sex now"

You can't. Once it comes out of your mouth it's gone. All you can do is learn from this mistake and think before you speak.