How do i deal with getting over someone i have never been with???

here goes...i have this really big crush on one of my teacher, from the first day i saw him its like i fell inlove with him. yea i know i say crush at first...but thats what i thought its been 6months and its like the more i see him my feelings start gettin stronger and stronger....did i mentioned havin a boyfriend? i do thats y i really don't want to get involve with him (teacher) but how do i deal with seeing him every other day and dealin with the nervousness whenever am at cl. at times i tell myself that its just infatuation but how can i be infatuated with someone this long?? its really hard for me trust me on that if you ever know....i spend alot of time with my boyfriend to get him off my mind it works sometime and another time its killing me its like i need him so badly bring tears to my eyes and i know i don't want to do anything stupid especially to rein my relationship with my boyfriend....