My partners best friend tried it on

So me and my partner have been together for 6 years. We’ve got 2 kids, a house and are very much in love. His best friend comes round often, he helped us move house, put up furniture etc. He’s always helped us out, baby sitting and stuff like that. Well, the weekend just gone me and my partner had a child free weekend. They where staying at grandparents. Any way, we was at the bar having a drink and bumped into a load of my partners friends and their girlfriends. Which was nice!

Side note, the best friend friend had a girlfriend for 8 years and they split up last year. He’s been single since and I’m very close friends with his ex girlfriends

Anyway, we was all out and having a drink and laugh. All of a sudden I notice the best friend staring at me, I tried to ignore it but it was so obvious. So I just joked it off like hahaha what you staring at have I got something on my face. To which he just laughed. An hour or so later he pulled me to one side whilst everyone else was occupied at the bar and what not. He then proceeded to confess his undying love for me! He literally went in for the kiss and I pushed him away. He told me I’m all he thinks about etc you know the usual ‘I’m in love with my best friends girlfriend’. Then everyone else came back and he got really nervous. I didn’t say anything I was so shocked. Me and my partner got home and I was getting myself ready to tell him when the best friend messaged me begging me not to say anything saying he made a mistake and he’s sorry it won’t happen again bla bla bla. I’m just really stuck with what to do here. I mean, they’ve been best friends since they where kids! It would kill my partner, that absolute betrayal would really hurt him.

I feel like it’s my duty to tell him, I mean if my best friend tried it on with him I’d be devastated. I would want to know. But are men the same? Would he want to know? 😩😩😩

I mean, he comes round the house often surely we can’t just act oblivious to it all. What am I going to doooo??

UPDATE

So I told him. I knew he deserved to know I just didn’t want to hurt him. You guys, these where the best friends ever. I’m still shocked he’s done this. My partner was devastated understandably. He confronted his friend to which he turned round and said it was me that came on to him 😣. Luckily I still had the messages of him begging me not to say anything. He then started saying all this shit ‘oh are you gonna let a girl come in between us’. My partner shut him down and said I’m not just a girl, I’m the mother to his kids and the love of his life. So they aren’t friends anymore, my partner is still so gutted. But I know now I did the right thing, thanks everyone