I found an add my fiance posted online looking for a fem to have fun with. Is he gay? What should I do?

My fiance and i had been together for almost 2 years. Everyone tought he was gay, but I just tought he was a little feminine. He proposed to me, met my family, and my friends. At some point we even lived together. He always thought I was cheating on him, he even went as far as installing an app on my phone that forwards all my messages to his phone without me knowing, and he charged my account for it. The last 4 months, he said he couldnt trust me bcuz he saw me dancing with my guy friend at a party. He tried to make me feel bad about this for 4 months. Until recently, he told me that he only engaged me bcuz thats what I wanted :/. Then he tell me that he doesn't think he is an emotionam guy, or maybe he just doesnt love me. So we broke up, and 3 days later he calls me begging me to go to lunch. I finally give in, n he tells me that he went online and checked my tex messages, he just wanted to trust me, buy he does now and he will never look at it again. Lie!! This application was still on my pgone, I had to find out on my own that he installed it. It didnt just do read my text online. Anyway, so I tell him that we should stay apart, give me time to trust him again, but he got upaet, called me a slut, said I wasnt trying to work things out. So I left it alone. The next day, something told me to check his email. All this time this would have been the only time I felt I should check this based on how he had been acting. I tought to myself u cant be this paranoid for no reason. So I checked his email, and sure enough I find adds stating that he is looking for a FEM to have fun with. The guy sends him pics with girls clothes on, tells him that he is a cross dresser, and my fiance sends him his #!! Im so upset, im hurt, im confused. I have never brought a man to my family, and thia is what happens to me when I do. He keeps begging me to get back with him, says he is sorry, he is just obbsessed with sex, he didnt even meet up with the dude. But I DONT TRUST HIM!!! Help!