I spent a lot of my career in burnout, and understand what you are going through. The distress increases and decreases based on the events of the day. You will get through this. Stay for the bonus. Spring is a marvelous time to retire.
Practical suggestions:
When you are bored out of your mind: Mindfulness. Nothing fancy, take a few deep breaths and notice your surroundings-the view out the window, the pattern of a carpet, marvel at the work that went into the construction of the building you are in.
When you are stressed:
Gratitude. That you have had a career which allowed you to have security in your finances, unlike most. That you will soon be able to be master of your own time with the one you love most. That when you walk out that door next spring, you will have your first summer off since leaving school, and more freedom than you have ever known.
this is fabulous!. Thank you