So my best friend added this guy off my yellow, they were talking for around 2 days while she was at mine and she became hell obsessive, she told me to try talk to him so that she could see if he talks to other girls (of course he did I found him on yellow) so she went home and I was still talking to him, i told her I blocked him like she asked but the next day he came and picked me up from mine and we went to the nearest park kind of thing, where we did get sexual, but he didn't want to have sex just yet he wanted to meet up a couple more times, I still talk to both but he doesn't want to even talk to my bff anymore he just wants me and my friend keeps telling me everything he says when he's already told me... 

As you can see I'm a really bad friend, I need to know what to do?? Please and thank you guysss xxxx