Hi Sophiesdad, I Don't think I can give any help, but I just wanted to say hi, and welcome to the site. It seems that you have everything well thought out. You are having a lot of back problems and need your wife's support. You seem to like and love your wife, but due to the back pain have not been having sex for a long time. You are horny, and of late have been attracted to guys and have been having fantasies about them. You want to be honest and tell your wife, but don't want to hurt her. Yes I agree with you you are between many rocks and hard places. I am very glad that you said you have not cheated on her, it would just make things worse, trust me, I did and it did. If it helps to read my story, here it is.
http://malesurvivor.org/cgi-local/ultimatebb.cgi?ubb=get_topic;f=43;t=000020