Fantacizing - is it a form of cheating?

it is OK in a way as you will constantly cursing yourself that its bad, and committing such action will make you gain some more gunnah. and you start fearing ALLAH SWT even more and ask for forgiveness from the sher of shaitan.

if such thoughts are making you constantly fear ALLAH SWT, then its good. cuz this is what you are made for.

you are made Ashrful Maqhlooqat cuz this is the reasoning that defines you. you constantly have to judge your actions.

but if you blindly follow such thoughts, without considering your intuitiveness and how ALLAH SWT will react to your call, then its good to read Quran and find out how many nations were wipeout from the face of this earth.