Do you tell your therapist everything, or do you ever withhold embarrassing info out of a desire to not tarnish your image?

I'm trying to become comfortable with the idea of telling my T everything, but part of me wants to hold back in some areas, like talking about sexual fantasies I have (not with the T) that I'm ashamed of. Realistically I know that I should probably come clean in order to move past it and see it's not a big deal, but it feels so embarrassing to do so.

Anyone in the same situation?