Female friends?

My guy wants to have female friends. I have not been okay with it the 11 years we have been together. He had this female friend since high school and he says they are just friends. He is okay with me talking to her as well. Should i let him keep this friend? Would you?

Let me take it back a bit for the women who think I’m controlling. Him and this old friend had sex before me. And recently they have been talking multiple times a day everyday. I was okay with it at first because we set boundaries but then she started calling after hours 4am and the like. I am not okay with this. Also she is very single and has been for some time. He also deleted their text messages. What’s to hide if just a friend right? Or am i being paranoid? He says I am.