My (25M) friend (23M) is mad at me for declining to let him have a 3some with my girlfriend (23F) and I

My girlfriend and I have been together for 4 years. We are thinking about marrying each other one day. We have a good friends who is always there for us, I'll call him bob. Bob is a good guy and we have been friends for nearly 6 years now and he has always been a great friend to us. Bobs birthday rolled around recently and he said he wanted to go to the club to celebrate, we happily obliged. At the club, we were drinking lots, for the first time I decided to let loose and drink lots too with my friend. This led to me having a good time and not really thinking about the consequences of anything I did. I remember that I was asked by bob if he could have a threesome with me and my girlfriend and I never really remembered him asking until a couple of days later. He sent me a sms saying how he was sad that I said maybe because he doesn't have much luck with the ladies and he thought I was a bro so I would let him have this birthday gift but I said maybe and then when he asked me again I said no. I don't remember either of these things happening and I'm fairly sure I didn't say yes but I don't really remember. I don't know what to do and I really don't want to lose my friend.<br><br>Edit: I never agreed to any threesome and my girlfriend would NEVER be okay with this.<br><br>Edit2: I just showed my girlfriend his message and she is very angry, she loves bob like a brother and wants to break off all contact with him now.<br><br>Edit3: I showed him this thread, he says he's going to kill himself now bc he lost a friend and he knows what he did was wrong.