Is there a saying like "I don't believe myself"?

Could I say "I don't believe myself"? Like I am saying some facts that are so unbelievable that I am not sure if they are even correct. Or where nobody else believes something that I am saying and I then I am starting to doubt myself.

Solution 1:

"I can't believe what I'm saying, but ... "

is a fairly common (200 000 hits on a Google search) 'comment-clause', but the speaker usually knows full well and is in full control of what they're saying, and this is a further hedged version of "You're not going to like / accept / believe this, but ...".

"I'm speaking off the top of my head here; ..."

is sometimes used before a statement that one is not sure is totally reliable (but where one is trying to be factual).