Married but interested in outside threesome?

Just recently married to my husband who I love dearly. I am extremely attracted to him, wouldn't be with him if I wasn't. He's my best friend and lover.. I was having a personal conversation with a woman I have grown to become great friends with. This woman's boyfriend has been asking her how she felt about a threesome with another girl. She wanted to know how I feel about it and it got me thinking.. I have never put a label on myself because I don't just like girls but I don't just like guys either. I don't consider myself bisexual because I have to have a personal relationship with anyone I have sexual relations with. Am I wrong for being very interested in this threesome with my good friend and her boyfriend? My husband knows about this and acts as if it doesn't even bother him.. she wants to experiment with me before she brings me into relations with her boyfriend.. I don't know what to do..