Want to explore new ppl

I'm feeling very conflicted right now. Ive been with my boyfriend for two year that I love with all of my heart. and our relationship is the best place it could be. but for some reason I have this urge to want to have sex with other people (mainly a guy that in sort of friend with). 
I lost my virginity to my bf and I would never ever want to cheat on him. but I have this sudden urge to wanna try and experience of other things.. 
and I feel wrong for feeling this way. we talked about it and and my bf said he was open to have a threesome but not with another guy. but he said "if you want to have an open relationship we can but they have to know that I let you do it and that you have to let me do it too"
and I felt confident in my decision to let him know what I'm feeling. but now after talking to him I feel completely disgusted with myself. and i don't know if ishould go through with it