I like a boy but he likes my best friend

So basically,

My friend is friends with this boy and he’s recently told one of their mural friends that he likes her. However, she has told me time and time again that she doesn’t see them together and that she really likes someone else.

The problem is I’ve liked this boy since the start of the year but I didn’t say anything because she’s friends with him, now he likes her it makes it even more complicated. But it’s making my stressed as I really need to tell someone but she’s my best friend and I don’t want to make things awkward even though she has assured me they’ll never date. What should I do? Xx

Update : they were together at a party last night and she said they were under a duvet for 2 hrs cuddling ://