My fiance wants me to be a huge slut

He constantly wantsmwants to be naked all the time and ready to fuck anyone and everyone. I've always fantasized about doing porn and being a slut. We've had 4 somes and went to a swingers club once. It was fun but I feel guilty after. I let every body there finger me, it was so hot. But he wants more and more. I had a fantasy about getting gang banged but don't know if I can do it. He's begging me to do it and hundreds of men if I want. I have slight body image issues as well. I know I'm lucky to have a man that encourages me to be with men and women as much as I want. I really want to be an all out slut and fuck everyone, how do I do this without the nerves and extreme guilt after?