First, whether your favorite teacher is single or not, and whether his age is appropriate. If your teacher is single, you can pursue him bravely. If he has a family, I advise you to keep your love in your heart and don't show it easily. Because you like someone, you must want him to be happy, so if so, just watch him happy from a distance and don't bother.
Does the teacher know that you like him? If he doesn't know that he has a family, it's better to stay away from him, because if he continues, he may get hurt. If he knows, what is his attitude? If he has a family and is still good to you, think about it. Is such a man reliable? Will he be kind to others when he is around you in the future? If he is single, knowing that you have a good impression on him and he likes it, you can get along well with him and develop appropriately.
Thirdly, I think there should be a principle that you can't destroy the happiness of others in order to realize your own happiness. In this case, three people will be very painful.
I wish you happiness