What do you do if you and your friend like the same person? (More complicated than you think)?

Okay. I know this sounds extremely typical. Its not. I am a girl, I like another girl, and my other friend (whos a girl) fell in love with this girl last year, and shes still not over her but she has moved onto other girls, and she is debating about whether she wants to be with the girl we both like, or with this other girl. She is most likely going for the other girl, leaving the girl that i like, available. But apparently she still loves her. But she says its whatever if i try anyhting with the other girl. I dont want to hurt her by going after the girl. All i want is to experiment with her, and i know she will experiment with me. I also like this guy. I am not entirely sure if i really like like him, we are still getting to know each other. Is it going behind his back if i experiemnt with the girl, then see if i want to be with him? is that wrong? I have no idea what I should do. I really like the girl, and I am not sure if I am bi, or if I even really like girls, which is why this experiment is so crucial. But this guy, his mom really likes me, and the last girl he dated really hurt him, and I dont want to hurt him, his mom doesnt want me to hurt him .. and i have no idea what to do.

please no mean answers. thanks for reading ..