He says you're insecure- so his solution is to lie and therefore prove to you that you should be insecure?

Plus I don't buy his BS he was a wingman where the plan is to meet up with women.

Did he buy anyone a drink?. Did he sit next to the same woman? Did he dance with that woman? Did he know the woman in advance? Are they connected by social media or texts?

Inform him his lie destroyed your trust. Now he has no right to say "trust me". He's now made himself a liar.

This is a big deal. People divorce for lost trust as often as adultery.

Only he can rebuild trust. What's his plan? He can't say "trust me". At a minimum, to save his marriage he should volunteer : no more going out to a bar with the single friend, and 100% access to his phone and social media accounts.