downsizing my hamster cage?

[Deanna]

currently my boy is in a large living world eco habitat but due to my relationship breaking down he will have to downsize to an alaska cage, now i posted to a facebooks group and someone said this would be cruel but its my only option or i would have to rehome him as im moving into just a room and the cage wont fit, is it cruel and should i look into rehoming him?
i cant leave him with my ex as he wouldnt get the proper care