Why are Dad's soo unfair?!

Ok so my name is Melinda Grace but everyone calls me 'Gracie'and Im 13. And lately my dad's been really unfair to me and my twin sis Lissa because he let's our older brother Matt do whatever he wants but he doesn't let us do anything and he grounds us all the time. Like how a couple days ago Matt heard me tell Lissa about this boy that I really like. He gave me his phone number and I think he wants me to be his girlfriend. But when matt heard me tell that to lissa he told my dad that I had a boyfriend and I was hanging around boys all the time at school. So dad got all mad and took my phone and started to read the text messages that 'my boyfriend' sent. All the messages said was that he thought I was cute and he wanted to kiss me, they weren't even that bad. But dad started yelling at me sayin how I was too young to be flirting and talking to boys and that I shouldn't even be thinkin about boys. Bbut I wasn't even flirting and what's wrong with talking and thinkin about boys?! So dad kept yellin and I started to walk away and he grabed my arm and keeped yellin at me so I screamed at him to let me go and now he took my fone and my laptop so now I hav to sneak and use Lissa's and I'm grounded 'until furter notice'. Its just soo unfair! Matt has a different girlfriend every week and all dad does is laugh and joke with him saying how matt's jus like dad was when he was he's age but if I even think about havin a boyfriend dad goes nuts! That's not fair! Matt's only 3 years older that's not much of an age difference. Is it bcuz I'm a girl? Isn't he being mean and showing favorism just because Matt is a boy?