Marriage advice please

[Bubblesquirt]

Hi I just need a bit of outsiders advice please.
So I live with my OH and DS and DD. I took DS away for a few days with friends while OH was home with DD. When he got back he said he had his male friend round. Yupp fine whatever glad you had company. I used his phone to ring mine as had put it down somewhere. His friend is recently single and other friends have fell out with him. Something made me read their WhatsApp messages. I know it was wrong but I did. Well apparently a girl came round the same night and friend was like she was hot and he understands why my OH smashed her. OH is saying it was when they were younger and not while we’ve been together they know each other now through work. I just don’t get why he’s lied and he’s upset at me for looking through his messages and also messaging her as I sent her a screenshot of his friends convo. He puts it down to banter and he shouldn’t have done it.

What did you want to achieve in sending it to her?

Do you know the woman? What is his reasoning for not saying why she was over? Did you know they had slept together before and if not have you both disclosed your sexual history or is it just something that's never been discussed?

If I were him, I would be upset with you for looking through his phone and messaging her too. That is just embarrassing (for you), she did not deserve to be dragged into your marital squabbles. It doesn’t sound like he did anything wrong unless not clearing what friends he sees with you first is something wrong.

My exdh did this, told a friend of mine, In front of another male friend of mine about 'smashing' a girl (urghhhh), he worked with her, turned out it was about 8 months after we got married. He chose to lie to you, by not telling you something, but I don't know how you prove if he's been lying or not about when he slept with her