Breaking up with an ex is never enjoyable, but it makes it so much worse when they're in the same friend group as you. Even if you end on good terms, it still will be uncomfortable.
1. First, just try to avoid this situation all together.
Looking back, I regret getting into a relationship with someone in the same friend group as me. I should have known that it could never end well.
2. Try and make it less awkward.
Make sure you say hi when you end up in the same place, it will break the tension.
3. Don't pretend like it never happened.
You dated and broke up, it happens. Don't just act like it never happened, but don't make it weird.
4. If they are being awkward, give them some space.
You don't have to avoid your friends, but maybe hang out with other people some nights. If you are in the same place, talk to the other people.
5. Be honest with them.
If things are awkward, it's going to make things awkward within your entire friend group. Talk to them and make sure you guys can handle being friends so you don't have to put the rest of your friends through this too.
I hope no one has to deal with this situation because it is not easy to deal with. I should probably take my own advice, as I have not followed these steps, but good luck to you!