Its always better for the GG's to know up front . The whole thing . Mainly because this is who you are and lying causes us not to know who we are really with , half of you , part of you or someone else entirely !
If they go fine , they weren't for you .
If married , then yes all in one sitting , you don't have to blurt anything out but make time to sit down and have a long talk. I tell you the broken trust is worse than the clothes and compounds the shock of wondering who this is in front of me .