Singapore Customs reviews and complaints

I am a Russian passport holder, living in Hong Kong. I have arrived to Singapore for a vocation visit with 2 small kids (3 and 5y.o) on April 6th 2015. The officer asked me why I had visited Iran before (he saw my Iranian visa). I explained him a reason (my husband is Iranian). I asked the officer why he asked about it. He took my documents and brought me and kids into the room, where they kept people with passport/visa issues. Kids and I stayed there for a while. Then they brought me to another officer, who yelled at me. The next officer said that thay have right to ask any questions they want, but people have no right to ask questions back (even though we were the only in the que, did not take any time from anyone)! They took my finger prints and kept me and kids for a while while the officers were going through all my visas in the passport (even questioning Hong Kong visas). Kids were hungry and tired! This is UNBELIEVABLE to be treated like that in a touristic destination! I am truly shocked of Singaporean customs! Which right do they have to intirigate people and humiliate them like that?! This is the first and the last time I am here. There are much better destinations to spend vocation! Mood is definitely ruined for the whole vocation! Badly regret of coming here!