Boyfriends old friend problem

Hey guys so I’m in a bit of a pickle here so let me explain... Before my boyfriend and I started going out he had this best friend and I was cool with her and after we started dating they slowly grew distant and I felt bad and I tried to like stay away so they could be close again but sadly it didn’t happen. My boyfriend and I have plans tomorrow to hang out and he says that she out of the blue called him and said she wanted to talk to him and I said we should cancel our plans so he could be there for her and he said I should go and he also says that she wouldn’t mind me being there and he even sent a screenshot of her saying she’s okay she just needs someone. My problem is that I never had that friendship with and I feel completely out of place being there and my boyfriend keeps saying he wants me there for support because he also feels like it’s been such a long time but I said I could wait or do my own thing and they could talk. What do I do ?