Ok, so in case you don’t realise, you’re doing with your friend what you should be doing with your wife.
I doubt your wife is jealous, I bet she’s pissed off that you’ve been together for decades with all that invested emotional effort and time and you’re trotting off to socialise with someone you work with and enjoy chatting to after work which means you’re not doing it with her.
Affairs aren’t just about sex. I think many men don’t realise that. Think about your relationship with your wife and how you consider her. Is it just based on sex or is there a whole load of other feelings involved? Going off and just shagging someone is awful and is a betrayal, but having an emotional affair is worse IMHO. Sex can be just sex, but sharing and enjoying an emotional connection and closeness with someone who isn’t your spouse is a massive betrayal that I don’t think I could come back from.
Yes, people can have friends of the opposite sex without anything happening but it’s really easy to cross boundaries without realising you’re doing it. What sort of things do the two of you do together when you’re socialising? When you’re out, would people think you’re a couple?
Think about what “jealous” means:
feeling or showing an envious resentment of someone or their achievements, possessions, or perceived advantages
Your wife shouldn’t be put in the position of being envious of the relationship someone else has with her husband.
If you think you are completely justified in having this friendship and are unwilling to change anything then I can guarantee you will be spending your latter years on your own and will have absolutely no idea why your wife suddenly decided she wanted a divorce after so many years of being happily married. Women, eh?