I can totally empathize with this. i feel the same about my husband, he is my best friend and the answer to all my prayers. So when OCD came along and took an ACTUAL real event of a time i went to watch a movie and made out with another guy a few weeks before i started dating my now husband, it turned it into " well what if it WASNT BEFORE you started dating, but after? what if you cheated on your husband from the very start" and let me tell yoooouuuu that ATE-ME-ALIVE. my husband loves to give affection, and tell me how wonderful i am and how much he loves me and when i was stuck in the OCD false memory i felt SICK, i felt like i didn't deserve his love because what if i cheated on him? after 5 months of HELL trying to figure it out, going thry old phones, trying to track dates and time, i even reached out to the guy i made out with to see if he remembered( 4 years ago) so naturally he did not. all of my searching only made things worse, it made everything feel more real the more time i spent on it. i finally started medication because i was making myself sick over it, stopped eating, missed work, kinda lost my mind for a bit, and started working with an NOCD therapist and we came up with some tricks that helped me stop ruminating about this. the biggest one, was " if it didn't matter then, it doesn't matter now" which basically means that... i know the type of person i am, i know that if i ever actually cheated on my husband i would be SIICK with guilt and would confess immediately, so for me to have gone 4 years of bliss then all of the sudden, we moved into a new house ( big life changes often trigger OCD flares) and one month later, now I'm panicking over something 4 years ago??? but i didn't panic at the time??? hmmm, that tells me its OCD, its uncomfortable yes but its simply not real.
You seem like me, you seem like if you were to betray your wife, you would confess immediately... so just use my phrase " it didn't matter then, it doesn't matter now, so it probably never happened" ( i use the word probably because its a way to strengthen your brain to accept uncertainty) it doesn't mean there is actually a chance something bad happened, it just means certainty doesn't exist for ANYTHING and its important to embrace that. i even acknowledge that sure there might be a 1% chance i did cheat on my husband, i have better odds of winning the lottery lol, a 1 in 1 million probability is not worth my time to analyze, that is what you have to tell yourself. a .5% chance of your fears begin true? HA! ogo buy a lotto ticket, see if you win, becuase with OCD, that's how convincing it is. don't modify your behavior to satisfy OCD. keep working with this co-worker as if nothing happened ( because it didn't) and just remind yourself 100 times a day if you need to, " didn't matter, doesn't matter, not important" and you WILL get past it. I'm over my issue and SO happy with my husband.