"It is the actual truth, and I will tell you about it."
Explanation:
The first sentence is a simple description of himself, nothing in the sentence indicates something of the past. In the third sentence, while it can seem to indicate flashback, there is no other context within this sentence or words used to fully confirm this. The second sentence is what I believe to be correct, the words used, "and I will tell you about." explicitly state that a previous event of his life or flashback will now be told in this story.
