I Was Convinced My Husband Was Cheating On Me

I hired someone to find out who he was cheating on me with, month later nothing, told me all he does is go to work and come home so if he is doing anything it is at work. I have been to his office area and there are really only the bathrooms and a few other places something could happen but honestly I think I just wasted about a thousand dollars to find out nothing is going on. I track his phone, always check texting, email and anything else I can on him and have never found anything even remotely close to cheating. He is never worried about anything, we share a laptop at home so not like he can hide anything there, I seem to be the one with a porn habit and not him.

So now I feel guilty doubting him, he even commented a few days ago that another one is awesome, referring to me offering him another blow job in the same day. When he gets home from work I ask him about his day quite often following him right into the bedroom thinking if he did something at work there would be evidence left behind like suck marks or something feminine I smelled on him. I was literally giving him a blow job just so I could see his cock right when he got home and never found anything. One day he even told me he was not feeling that great, he was coughing and sneezing a lot with a stuffed up head but I still pushed wanting to give him one and nothing, all was good and I probably caught his cold. I just cannot get it out of my head for some reason then I guilt myself into sexually pleasuring him as punishment to myself. I even lied about wanting to be spanked one night, I hate it done to me because that is what my dad used as punishment and I thought I deserved it after wasting the money. So how do I get this out of my head? Why would I after like twenty five years of marriage suddenly be convinced without anything evidence related to him cheating on me just be convinced that he is? Drives me crazy as hell.