Family Ties/Let her calm down, try and talk to her in morning.
You think it's best with all that happened to give Heather some space and time to deal with what you have done before trying to beg her forgiveness. You can tell from the sounds of the doors opening and closing that she had retreated to her room and for now hasn't spoken to any one else. It's best not to force her to talk till she's ready.
After a few hours of broken sleep you get up and grab your gear for the trip and head down stairs to find your parent discussing a note left by Heather on the fridge. In her words, Nicole, Heather's best friend, had had a death in the family and your sister rushed over to offer support before any one was up that morning and there was no way she could go on the trip in her best friend's time of need. Nicole had been you big sister's bestie since kindergarten and had been and honorary member of the family ever since. It made sense that to her house is where she would go considering what happened.
You quickly ditch your bag behind the couch and drag your self into the kitchen, complaining about a stomach virus causing the twins to get really impatient. After a brief discussion it was decided that you could stay home and your parents and the twins would go on the trip.
With your parents out of the way and a week end worth of time to set things straight with Heather you start thinking over how you wish to proceed.