I had a threesome with my best friend and her boyfriend

After a very heavy night of drinking I went back to my best friend's for a 'girls' sleepover of sorts (we're both 19) but her boyfriend of three months (first real relationship she's had) managed to get himself invited too.. Honeymoon period and all that I suppose, they have been practically living together for the past month and a half.. we all ended up sharing a bed and my best friend began to give her boyfriend a hand job, I was pretty smashed at this point and so merely laughed about how much I was 'third wheeling it' to which point my best friend started to try and get me to join in, to begin with I felt awkward and uninterested (I'm not attracted to her boyfriend in the slightest) but eventually decided "fuck it, make her happy" how my drunken mind works, I do not know! So things got pretty intense and I soon sobered up and left the room. When I came back the couple were just 'finishing' I then awkwardly stumbled into bed and pretended nothing happened, but my best friend started crying and wouldn't let her boyfriend touch her at all. He left the room and she told me she felt weird (she only lost her virginity three months ago and is now practically living with the guy so I concluded she moved too fast) however, when he came back she hid away again and asked us both to leave, which I was happy to comply but her boyfriend wasn't.. he wanted to stay despite her making it clear she wanted to be alone. After a little arguing we both eventually left her to have some space and hopefully get over the ordeal. However, waking up the next morning, sober, I feel terrible about the whole thing and am terrified this is going to destroy our friendship, she already called off plans for that night because she didn't want to face it but made it clear that she was 'fine' for which I don't believe! I know it was all a mistake and I can't help but feel guilty and awkward, I should have been more sensible but there's no going back now.. I'm just not sure where to go from here? I really don't want to lose her as a friend! Any opinions and advice would be greatly appreciated!

Okay so first of all don't worry too much about it if you were dragged into the 3some as neither you or the boyfriend suggested it it was your friends drunken mistake. Although her reaction properly is that her boyfriend has been with another woman worse of her best friend. Remember you have done nothing wrong except please your friend. What you do need to do is sit and talk with her and why she decided to have sec why your in bed next to her. Her or her boyfriend should of had some respect for you being there. Just talk to her see how she's doing what's her reaction and work through it

Just be there for her she's going to eventually need someone to talk to. Show her your there and that you care and tell her that when she's ready she can talk to you. Seriously this happened with my man of nearly 4 years and it was with me and my best mate and him she came onto him and tried to make him get pregnant didn't work now her and i are not friends cos she also got my kids taken off me as well.