first of all, you aren’t abnormal for feeling this way. you’re likely a teenager going through typical hormonal changes lol. pause for a moment, dissect the feeling and acknowledge it as fantasy and move on. it can be helpful to minimise time spent with them and keep yourself occupied with hobbies, other friends, study, anything that diverts you from these thoughts from reigning spotlight. like op said you may learn this lesson through experience, so if there IS any intent for you to pursue a relationship with them be prepared of the risks of potentially jeopardising that friendship. discussing things can be kinda 50/50 but at least you know 100% that you will alleviate any uncertainties you have regarding their feelings about you. but before this, draw a distinction. ask yourself if these feelings are based purely on desire, the attention or kindness they show you or deeper. don’t be hard on yourself :)