I'm still a bit of a noob to this game -- but not to 4X gaming. From all that I've heard, the AI in this game never "cheats", and if so, then seems to me you were just out gamed here dude. In any event, you posted here your inital frustrations, and that understanable, but please consider posting instead an after action, or "lessons learn" report -- or at least summerize a "5 Why" study on how you lost that game to an honest AI -- making sure to include game settings.
Anyway, I'm curious why didn't you anticipate the Dread Lords might possibly have advanced technology allowing their ships to appear "out of no where"? What sort of defense grid did you have in place and were you keeping your ships upgraded. Also, if you had the "biggest" military -- why would you not expext the other galatic species to eventually view you as a threat? Besides that -- if in a multipayer game where you gave me every tech I asked for -- I'd own you in very short order.