My [M] partner [F] shares NSFW photo with friends – unsure how to react

Apologies if this is the wrong subreddit to post this on – have been looking for some time for a place to ask advice on this and this place seems to fit.

So I’ve been with my partner for some time, and we’ve been part of the same group of friends for longer. We have a fairly open group and do tend to talk about sex quite freely which is fine. I have a friend, let’s call him Jeff. Jeff has been attracted to my partner in the past before we were together (only sexually though) – he flirts with her but it’s all in good spirit and we all know that’s all it is. Jeff has recently started seeing a girl outside our group and feels the need to overcompensate by acting like he’s never been attracted to my girl whatsoever. One way he’s been doing this is repeatedly saying my partner is flat chested, which is laughable given she’s busty for her size and he’s commented as much in the past.