I'm sorry to hear you failed your exams as a result of the breakup and how depressing it was celebrating your birthday. Your boyfriend has texted you to know if you've moved on. Have you moved on are you still longing for him? Again he wants to find out if from your response there is a chance of getting back. His motive might be genuine by finding out if the breakup affected you negatively (though it's hardly the case), or it might be mockery when he finds out from your response it has been hard for you to move on or wants to know if there's a chance to get back together.
So, what should you do? Though it's hard to move on after a breakup, it's possible. I would advise you reply to him that you're not fine because his dumping you hurt you to the point you were depressed, which you are, and as a result of depression, you failed your exams. But, let him know you'll be fine because you're moving on with your life. Even though it's hard to move on you'll make it.
After you've replied don't reply to another text he sends. If you do so, you'll long for him which will increase the hurt and depression. You'll find it hard to move on. Maybe he was sorry for dumping you. It doesn't matter. You have to move on with your life. I have written an article on how to heal and recover from a breakup. Read it on how you can move on after a breakup. Don't forget to thank him for everything and wish him all the best. Don't work on reviving the relationship because it will revive the the pain which will affect you negatively as you might develop acute depression. Maybe several months or years after you've healed completely you'll know if it's okay to reunite but not now when you're hurting.