Bicurious

I’m in a relationship with a man, and I’ve always been bicurious. I’ve expressed how I felt to my boyfriend and he said it was okay for me to explore... as long as he could watch. The only thing is... I’ll feel like I’m cheating if I’m with another woman, and I’m not sure if I’m ready for a 3 sum yet. How do I go about this? 😩 HELPPPPP