Threesomes

My friend for almost 10 years asked me if I would be interested in having a threesome. I would say this before getting into it but yes we’ve had sex once before earlier on this year but the downside is he has like a girlfriend of 4 years, they are always on and off and he always cheats on her and she also cheats on him with some of his friends but idk why they still together lmao. But anyhow he ft me and we were chatting and he asked me, I wanted to try it but once I’m over 18 (I’m 17) but I didn’t decline I soon as he asked so I just asked him if I were to say yes who I would be doing it with and he said it’s “my choice” 🤔 lol I’ve been thinking about it for two weeks now if I should even do it 😂 I mostly wanna do it with two males but my body count is already 4 and I don’t want it to raise anytime soon. So should I do it anyhow with someone of mine of his choice or should I do it with a girl? I have a few bi friends so it shouldn’t be hard 😂