I think my best friend and I like the same girl. What should i do?

My best friend is a . My friend with benefits is not but she'll sleep with a girl from time to time. Anyways it was my bff's bday last night and we were at a xmas party hosted by my fwb. At the party i saw my bff and my fwb making out. My fwb baked a cake herself for my bff. i thought this was really sweet of her. i went outside with my bff to get some air and she told me that if my fwb is ever done with guys she would date her because she is a sweetheart and a good mom. i completely agree but she's a total slut. The problem is i just recently started to actually like my fwb. im afraid to tell my bff this because she always calls my bff a hoe and now she finally said something good about her and it seems like she might like her as well. i dont want to fight with my bff. she is the only woman i trust other than my mother. So what should i do or What should i say to my bff?