lost of erection

General

i am a male 44yrs old and have been married for 24 yrs to my wife..we had alot ups and downs in the past years and find it hard to go through problems again...the last year or so ive been having problems with my erection. when it comes to intercourse i lose my erection and get nervous. i dont want to dissapoint my wife any more. Although i am very attracted to her and do desire her alot, but get nervous when it comes to intercourse. This problem has occured after she found some porn vids that i had hid from her. i was so ashamed when she approached me that i cant get over it.. she totally freaked when she found them and i cant seem to get it out of my head.. We have discussed this matter and she told me to get over it. What can i do.. really like for someone to understand my stress.