Am I over reacting??

So I was looking at my husband Snapchat this morning, and I found a thread of Messages to another woman… They were mainly emoji‘s”😉,😎,😄” responding to her story posts… Which happened to be Slutty ass selfie‘s… It also look like she sent him a few personally… One Photo she sent him directly on Halloween in all black lingerie, which he replied “dirttttyyyy😎”

I flipped my shit… Confronted him, and he said she keeps sending him these photos, and he hardly even knows her! Am I overreacting?