A person in love with you is likely to be vulnerable to you, easy prey for your abuse and exploitation. Your first responsibility toward the person you have made fall in love with you is the responsibility not to take advantage of this person's special vulnerability to you. This responsibility is all the harder to deny because it does not require much effort on your part. You can just be -- gently -- honest about your feelings and then keep your distance.
If you were rather active and deliberate in making the other fall in love with you, then you may in a sense be and/or feel responsible for her unhappiness. And this may seem to be a reason to show care and concern for the other, even at some cost to your own life and ambitions. But then you must also ask yourself whether you can be confident that you (of all people!) can make a real contribution toward helping the other get over the unhappy situation. Without such confidence, it may be best just to make do with the above simpler responsibilities: do not take advantage and be gently honest.