Make it simple, and tell the truth. That way you don’t have to work at concocting some elaborate tale.
The truth may not be pretty and it may not be entirely comfortable, but it is the easiest and kindest thing you can say.
Now, all of that is true, but it still needs a caveat. The truth should never be used as a weapon.
If it proves to be too hurtful at the moment, then it shouldn’t be shared, and neither should any alternate story.
The truth is simple, easy, straightforward, and should ideally be shared with an intent of kindness.