Most of the people have faced such conditions in their life at once if not they would have fantasized about the adultery. There is not a single man in the earth without an id, an inaccesible part of the personality which has no organization and collective will but only seeks the pleasure. It is the ego and superego, accessible parts of the personality, controls to morally to do the right things. So what you did is the part of everyone's life. You don't have to regret a lot for what you have done. The things that you enjoy today will become worthless in the future. So you don't need to blame yourself for what you have done. This is the instinct desire that everyone has. 90% of the single guy who had never been in relation with anyone would do the same thing that you did.
Just concentrate on your study and don't make the mistake again if it later make you feel morally wrong.