Totally agree with Phoenix - these are not the actions of someone who loves you and wants to protect you from harm. He is literally turning the whole thing around - "Oh, you found something (along with other semethings in the past) that lead you to believe X about me? How horrible that you'd believe evidence over anything I tell you! You have no trust! I'm telling people you don't trust me and what you've accused me of!". Trust me when I say that if he DID tell people, it wouldn't start off with "She found gay porn on my phone....". It'd just be "She is accusing me of cheating on her. I would NEVER do such a thing. I'm a great, faithful husband!" He would make it look like your accusations are baseless.
Personally, I'd call his bluff. But that's because I don't take well to threats. "Go right ahead and tell everyone that I think you're gay. Then I'll tell them why I think that. Go right ahead. Wait, let me start it off for you. I'll just send out a group blast starting with "Found more deleted gay porn", followed by examples of people having told me repeatedly over the years about you being gay, etc. Did you want to help me word it?" Hah. Watch his head start freaking spinning.
Kel