What do I do if my best friend and ex like each other?

Hey! Thanks for clicking on this and hopefully taking the time to read this and replying with advice! I need major help with this problem.. Okay, so I was talking to this boy (C) and we liked each other for a very long time and things got pretty serious but we never actually dated. My friend (S) knew about C and I. C and I eventually lost contact and basically stopped talking which really broke my heart. Meanwhile, S started liking this guy (B) who was C's best friend. Long story short B and S didn't work out and C and S got pretty close.. He later told her he liked her! She likes him too and she knows I'm still not over him. I told her that I didn't care about it because I didn't want her to feel bad but she keeps talking about him all the time and it's hurting me so much. She's so absorbed in herself that she doesn't even realize how much it hurts me.. my other best friend (P) has told her that I'm not over C but she doesn't seem to care. I cry all the time because of it and I will send S pictures of me crying and she will keep on talking about her and C. Please help me because I honestly don't know what to do anymore... Thank you fro reading this!