Friend flirting but has a long term partner

So about 15 months ago me and my boyfriend joined a gaming group that meets once a week. We have made some fantastic friends and always have a laugh. A few people have become good enough friends that we hang out in general as well go to each other's houses etc.

We all have innuendo and dirty banter as you do but lately one guy who I count as a good friend, a type of friend you can talk to about more serious stuff and be a bit more real with, has been starting to take it too far.

The last few months we've been sending more texts and doing the usual banter but he has started talking a out sending naked selfies etc. I deflect with more silly messing around type jokes and so far it had been keeping things light.

Then today he mentioned if I would actually be intrigued to see him naked. I replied with that I'm only interested in seeing my boyfriend naked and he said he understands but is disappointed because he finds me very attractive and that I am beautiful with a shining soul and a winning package. He said he hoped he hadn't ruined the friendship by admitting this.

I want to stay his friend as he is lovely and I enjoy knowing him as a friend. I am not attracted to him (he is 14 years older) and I have been with my guy for 7 and a half years and I love my guy so much. So I said no it's always nice to be told that someone finds you attractive and not to be embaressed and we are still friends.

The thing is he then said 'ok I'll delete my message thread'. He has been with his lady for 18 years and they live together. Like a married couple though not actually married. I wonder should she know about this. What if I had been a less faithful person or single and got into something with this friend? Would he have cheated on her?

I haven't told anyone about this and am hopìng we can just forget about it but part of me worries about whether she should know. It's human to find other people attractive and flirt every now and then, I don't think there's anything wrong with that so long as you don't act on it.

If it is consisted that he is cheating by offering to send naked pictures then do I tell my boyfriend? Am I in the wrong to not say anything. He is friends with him too.

Opinions on how to handle this would be very helpful. Thanks.