It's important to remember that we have all been on a long break, both teachers and students, so if you are dreading going back to the classroom, your students probably feel the same way. So, whatever you do, they'll be okay with it.
It's also important to remember that the first few days, even the first week, can be a transition period or a new beginning. This is the time to re-build relationships with your students, some of them may have already forgotten they like you!
The first day of school is perfect for these activities:
I really hope these ideas are helpful. I highly recommend to plan at least your first day back BEFORE you go on break, so you are not stressing out during the break and you have plenty of time to rest.
If you do HAVE TO work the Sunday before going back to work I suggest to put it in your calendar for a specific time and only work during that time. Be your most productive self during 1-2 hours of your day and then forget about it!!! (This is why I highly recommend to work in the morning if you can.. just get it out of the way!) I also recommend using the Pomodoro technique, which will help you put all distractions aside.
I'm sure you will be great!!! Don't be too hard on yourself!!