I understand your doubts as posted above. I know that people sometimes regret hurting a third person in their own pain. And for that reason it's best to take things slowly and be honest about where you are at IMHO.
I think the betrayal is a lesser thing to me. It has been my choice not to date as I am still M. But I could just as well have chosen otherwise and not worried about it. After all, my H's infidelity has broken our M contract just now.
However, the fact that I would hope to save the M if I could is a biggie for me. It doesn't seem fair to become involved with another on that basis. And I am surprised that your friend's friend calls you a keeper on this basis - unless she doesn't know that. I would be urging caution if I were her friend. Particularly with the benefit of recent horrible experience - red flags for me! But I may be extra sensitive.
So - I guess that's the message from me. Slow and honest. Honest that things are far from resolved with your W. And that it would be soon (and possibly unhealthy) to start another R. But friends and some flirting where no-one gets hurt? Very nice!!
T 13 M 7 Me 48 H 46 SS 15 BD 7.14 PA D final 5.16 (H filed)
We receive & we lose, and must try to achieve gratitude & embrace with whole hearts whatever of life that remains after the losses - Dubus