My BFF found my husband on a dating site

A couple weeks ago my friend came to me with bad news. She told me that she found my husband on a dating app. Without asking me, she set up a fake account & started taking to him. She has the messages saved & took screenshots, I haven't seen them yet because I'm not ready to look at them. From what she tells me he was immediately ready to meet up with her after he got out of work one night. Her story lines up with when he told me he was going to be late & then came home on time & was in a lousy mood the rest of the night. She turned him down obviously & basically gave him an excuse to not meet him so soon. The conversation that they had was explicit. He was, from her, completely ready & will & apparently prepared. He discussed where they would meet, where they could f***, which ways he wanted to do it, what he wanted her to do with him & what he wanted to do with her, everything.

I know what she did was out of love & to protect me. But I feel like she's meddling in my relationship a bit too much. I want to confront him & have all the evidence I need to back me up though. He's never cheated on me before, that I know of. I thought we were happy? I don't understand. We're best friends & don't keep anything from each other. Why wouldn't he tell me he wants to hook up with other ladies? How can I talk to him about it? I'm not the type to fly off the handle, but it's been so hard to keep my mouth shut while I have a million questions swirling around in my head. Please help me. Sorry for the long rant.