I've been through something similar myself. My longest relationship was with a widow, and I always felt like I was just there because her true love was gone. If he were ever to be resurrected, she would've immediately left me for him.
I think some people can manage that, but if you love deeply and have a degree of emotional intelligence, it's probably not for you. I could see the part of her that was missing from our relationship. I'll have love for her till the day I die, but it's for the better that it ended.
As for your particular situation, I think I'd have a very hard time having that first reconnection take place with another person present. I know I wouldn't be able to be myself under those circumstances, and I'd feel robbed of the chance of having a real interaction.
I'd also be looking at how the friend received me. People always vent to their friends after a break up. And if it's a close friend and they don't seem like they're being either obviously or slyly negative to me, that'd let me know that my ex probably hasn't said too much bad about me--which might mean I was a really great person to be with or that they're not spilling the beans because they hope things won't end there.
But when the other person ends it, what can you really do but let them do what they will? When my most recent ex left me, it was devastating, and she's expressed lots of feelings for me ever since. But I secretly thought it was for the best, and I wouldn't try to change her mind regardless, so I never tried to get her back. She's off with someone else now. I'm not totally healed, haven't completely reached the degree of feeling I had for her again, but I'm doing alright--optimistic. The universe is infinite in time, space, and possibility. We'll always be able to create a tomorrow for ourselves that's every bit as full as yesterday was.
Haha sorry if you got more than what you asked for here, but I'm a couple hard seltzers deep while watching the USA vs France for basketball gold at the olympics, so a rant was bound to happen!
