I think my dad is practicing polygamy

My father is Egyptian and my mother is American. They were married in Egypt, when they first got married my dad was fairly rich. But when the economy crashed he became poor. After that, they moved to America. For the past couple years we've been barely scraping by. I am the only child and I'm 14 years old. My father works as a security guard at a graveyard. He only gets to see us on the weekends. I don't know why he can't quit his job and find a better one but he won't. I'm starting to think my dad has a second wife that he's sending money too because he never buys anything for us. He claims he doesn't get paid enough. But I remember him taking me to Egypt once and he spent a lot of money there. He bought me everything I wanted. My mom is suffering so much. She's constantly sick because she doesn't eat enough and whenever she asks him to buy her food he always complains that he doesn't have enough money. I think my dad is lying and he's sending all his money to his other wife. Why would he spend money on me and not my mother? He doesn't even buy me anything here. But whenever we go to Egypt he spends a lot of money on me.