so yesterday someone tried phalanx me. thankfully, their fleet was to arrive 30 mins after mine so i was safe. my question is its only a matter of time before my fleet gets crashed, more specifically, my fleet has to get crashed until i get a moon, correct?

not necessarily, you can build 1667 light fighters and let someone smash it. that will give you a 20% moon shot. also if you fleetsave on deploy recall you can avoid a phalanx hit. just send your fleet on deploy mission to one of your planets and recall it halfway through. phalanx cannot see your fleet once it is recalled. hope this helps you