My friend is mad at me and I need advice!!?

Okay so heres the story

Okay well this is the the background info: Our Enlish teacher gave us a HSA English project to do and alot of people [including me] knew the answers were on the internet . Well Miranda [EX bf] just moved so she dosent have internet yet. So of course her being my bf I told her answers were on the web. Well the night before its due [mind you she gave us a week] she texts me at like 6:00 asking me to text her the answers [remember this is a 50 question packet and she does not NEED the web to do it ... ... because she can read the stories and answers the questions] Well I had my phone in my purse downstairs and was you know chilling out and relaxing all cool and didnt check my phone until like 12:00 that night [Being the sucker I am i probably would have told her the answers if I got the text earlier] . So since it was so late I texted her [mind you she goes to sleep at like 10 every night] and was like "I would but its like 11:48 and Im sure you have already done it" she probably was sleeping because she texted me back the next morning and was "No i havent" Right now Im thinking this is one stupid girl because if I didnt get back to her within 5 min. she shouldve done it herself. Anyway I text her back sayinging " well then I guess you have alot to do then!" she texts me saying "Shut up god" Me being really slow, didnt get it and was like "shut up god. thats and interesting statement" and she was like "whatever" Anyway that day at school she didn't speak to me AT ALL and she told our friend today thats shes not apologizing and I need to apologize. And Im like Im not degrading myself by saying sorry to make her happy when I didnt do anything wrong. Im like what am I supposed to be saying sorry for, theres nothing even for me to say sorry about. Im not going to say sorry for not checking my phone because its my right not to check my phone. All my friends are like she is overreacting. What do you think??

Oh and she copies my HW all the time. She would be failing AP Government w/o me!

If I would to say sorry to her I dont think I can ever be friends with her again. Why would I want to be friends with someone who apparantly only wants to be my friends with me to do my work!!!