A few months ago my girlfriend and I broke up (after many months of on-again off-again). Things were getting too serious for me and I made some bad decisions which I regret now. Toward the end of that relationship, I started hooking up with another ex and this continued until recently. I came clean to them both, and naturally both were furious and hated one another. However, now they have somehow become good friends - they hang out, talk, message each other all the time and I can't help but think that its all a little weird. Especially since both seem to have forgiven me and are acting like they want to start something up with me again. I really have no interest in getting into another relationship right now, they're both really great girls and the last thing I want to do is hurt them again. Problem is that together they contacted me and want to meet up and chat - the three of us. Should I meet up with them? What would I even say? I've got a really bad feeling about that...

Why bother? You feel that nothing good can come of it and you're probably right.

It's likely that they realized that hating each other was stupid since neither one knew about the other so them becoming friends is possible...but it was you who was doing the playing...so you can only guess from here on.

So anyway, leave it alone....but at the same time, you should learn from this and maybe stop using people.

I would leave it alone. No point in meeting with them, I can't even imagine why they would want to. Tell them "no thanks" and leave them both alone.
Make better choices next time.

Two against one? No thanks, even if they want a threesome.

No. It sounds like a potential stunt to do something to hurt or embarrass you in retaliation, or gang up in a conversation to make you feel badly for hurting them.

I would respond like this: "I realize I made mistakes with both of and hurt both of you and I am very sorry. I was immature and regret that what I needed to learn came at your expense. Both of you are tremendous people and I'm glad you've found friendship and support in each other. As for me though, maintaining a friendship is uncomfortable and I am going to move on. Thank you for your invitation, but of course, meeting up with two former girlfriends at once would be very uncomfortable, and not something I want to do. I give you a lot of credit for being willing to maintain a friendship, and hope you will accept and understand I need to move on."

If they were planning something nasty, the apology might dissuade them. If not, your unwillingness to be set-up is adviseable. Don't see or talk with either of them.

Two against one? No thanks, even if they want a threesome.

Bobbick comes to mind. Opt. out for the meeting.