Help. Girl Code!

So as the title says, I need a bit of help with girl code..

So rewind back to April 2018 we went on a family holday with the kids to Turkey. Our children made friends with two other children, and naturally both couples became 'holiday' friends whislt away. Nothing sexual might I add. Fast forward to now, myself and the wife get along well, the kids enjoy seeing eachother every now and again. Both husbands don't talk. I have the husband on social media, never been an issue, the holiday wife has Mr L on social media too. All happy and friendly never been an issue. The holiday husband has always been a tad flirty but nothing innapropiate. Now today, he has basically spilled his guts to me saying how he feels about me, how he wants us to go behind everyones back and have sex. Never mind that he isn't my type, that I am happily married and would never look anywhere else but he said how much he fancied me ever since he met me on holiday and saying how he likes my body and wishes I was single. Basically said he would cheat on his wife If I would cheat on Mr L.... ain't happening sunshine. I asked him to stop or I would have to block him, he didn't stop, so he got blocked. I have told Mr L, who is totally laid back about the whole sitaution (thank god) ... but here lies my issue. His wife isn't one of my best friends, we only see one another from time to time for a coulple of hours ..... Girl code is telling me I need to tell her how much of a slime ball this guy is, but on the other hand I am no marriage wrecker and I don't want to be in the middle of something like this.

Help, please!

Hm, personally I would tell her but I know that I’d hope someone else would do that for me if I were ever in that situation... I’d appreciate it a lot more hearing it from the other person directly rather than finding out some other way later on down the line