As someone who has struggled with this type of thing most of my life I will give you some personal advise as well as some from my therapist. Right now is one of the most important times to attack this. If you let this continue to eat away at your mind all day long it will literally scar your brain and become a part of you. You have to recognize when you are about to go down that dark rabbit hole of thinking about those pictures and immediately stop yourself. Best way is instant distraction. Throw yourself completely into your work, turn on a video game and immerse yourself, sing a song out loud or in your head, anything that requires the engagement of your mind that will block those thoughts. You’ll laugh at this one but I actually sometime imagine a little samurai in my mind and when a bad thought comes in I slap that thought onto a piece of mental paper and let my samurai shred it to pieces in my mind. Some of this is cognitive behavioral therapy, some of it is a combination of other strategies. It will take time to get over it but the quicker you attack it the better off you will be.