I think the growing narrative is that 45 is a political neophyte and not a legal scholar (hah!), so he didn't know what he was doing might be wrong. And, anyway, he was joking.
Glad you phrased it as "telling the truth." It's entirely possible that Trump has no memory of the event or has convinced himself that something totally different happened.
It would be therefore difficult to say he was a lying, a charge that implies the competence to form intent.
So, he better hope there is a "tape" of the meeting?![]()
We have become Planet X.What, no Planet X option ?
....
That said, IMO Comey is the more reliable witness by several orders of magnitude.
Supporting that, many observers note that FBI agents are trained to document everything, and their reports are generally considered reliable evidence in legal proceedings. I think the fact that Comey not only wrote his memos but shared them with colleagues at the time is decisive.