Hi ive just started a poly relationship with two girls– my best friend and the girl ive been dating for over a year over long distance. But honestly im a little mervous about it constantly bc im not sure if my old friend is fully okay with it. Would you mind helping me a little..??

This is an issue of trust and communication. It can be hard to read someone over long distance, but that means you two need to commit even more strongly to being fully honest and open with each other. 

If she tells you she’s okay with it, you need to trust her, and respect that she is an adult with agency who can speak to her own mindset better than your own internal nervousness can project it.

If you can’t trust her to be honest with you, and suspect that she’s just saying what she thinks you want to her or otherwise not being totally open, then one or both of you are not ready for a polyamorous relationship.