Am i in the wrong?

Partener of 2 yrs we got engaged at 18months

He says 2 months after engagement that he is feeling claustrophobic (even though im not clingy or anything and work hard)

And wants to sleep with his best friend(girl) to relieve that feeling.

After months of debating and arguing i agreed.

It hasnt happened yet because of covid but some sexting has been exchanged.

Just today i found out that he had kept some nude pics of her i asked him to delete in a hidden pic folder on his iphone.

He brushed it off as oh i didn't know you wanted me to delete them.

I have been cheated on before and manipulated.

Am i over reacting here? I feel like i am being manipulated again but who knows