Thank you, everyone, for offering me your words. A lot of this resonates with me, and it makes sense. I don't want to miss time the three of us can spend together, as it always feels good when we do. There is good energy in this situation, kindness, respect, and fun. While C and I have both had other partners, this is the first time that a three-way friendship seems to be growing, and I really don't want to step back from that. It's a new situation, and I'll allow myself the time it takes to let it evolve.
Communicate and do what feels right... true mottoes for poly :-) I really appreciate all of your replies. Got a lot of help from this thread :-)