Suffice it to say, meaning (1) let us just say or (2) I shall just say, is the subjunctive form of the phrase it suffices to say. It may be affixed to the beginning of any declarative sentence or clause, and it works wherever let us just say would work. It does not need to be set apart with a comma. One might follow suffice it to say with that, but the that is often unnecessary.
Suffice it to say that “veggie meat crumbs,” “soy butter,” and the abominable phrase “vegan mayo” are well-represented. [Salon]
Suffice it to say I am trying to end this terrible vestige of a different time in our history. [Baltimore Sun]
While understanding the distinction is a bit like trying to untie wet spaghetti, suffice it to say they both benefit financially from tax laws. [Foster’s Daily Democrat]
Suffice it to say that the film is full of character-actor experts, who can take a funny line and turn it into pure comedic gold. [Boston Herald]