Is staying the night at a friends house on a school night so wrong? Im 18 and a honor student in High school..?

So my good friend live in a court adacent to my street, and there basically my second family, id rather be there than at my house. I have just turned 18 3 days ago, and before this my parents would blow my phone up tellin me to come home at 11 and cuh, which i think is understandable. BUT, i told them whnei turned 18, i want more leeway..i have never done anything for them not to trust me.. and its right down the street, and if i come home in the morning in time to go to schoool, i see NO problem, So tonight i was watching Twilight, completely harmless and its like 12 and my moms like come home, and i told her no. and Then my dad calls, and blah. I say no, im stayin the night, when in actuality im walkng as were speakin, very pissed off. So am i in the wrong for wanting to be trusted and just stay the night at my friends? What laws can i quote to say there is nothing they can longer do to keep me in the house, i thought i was now a legal adult!