actually, is the second one.
Yo siempre digo la verdad.
You can use any form of the verb, but it has to be indicative. I have used the <u>present form</u> (the most used in these cases) of the verb "decir" (say).
<h3><em><u>MissSpanish</u></em></h3>
Do you have any place where we can talk on such as social media? I can gladly help you out.