Your resolve to keep the season "merry and bright" may be falling a little already. It's one thing to look forward to the end of Christmas, through Epiphany, and realize that it'll soon be over, but harder as we travel through it to stay positive and worry-free.
So take a mental break. Shut the door on the room stacked with decorations and laundry, grab your Bible, and settle your heart to rest in the "Christ" of Christmas for a time. It may be helpful to even set a timer so you don't worry about the next thing on your to-do list until after your break.
Some beautiful songs from Psalms, or a good-ole' Proverb or two is just enough to get back to a healthy state. And if you want to treat yourself, flip two books over and read a romance in Song of Songs (or Song of Solomon, depending on your Bible translation). Then, when your timer goes off light the Yankee Candle, turn on some music, and get back to it- it'll be amazing how much those few minutes with Christ will help with all the other details!