As you said it yourself, once a relationship has ended you are free to do whatever. If you feel good with your ex's friend, then be with her. Maybe she is your "the one and only". You should care only about your own happiness. And by the way, your exs friend should worry about this situation, not you, if she is going to be in a relationship with you.
The 'Ex's Friend' may feel it just would Not... Be Better suited to date because it is a Pinkie Swear thing. If She is a true friend of the Ex, she will say "No" to Joe Because she Knows that Friendships will usually Last Longer than a Shot in the Dark with Someone whom the Ex had problems with to Begin with. Good luck. xx
Would you want the drama and the issues that could come with that? Also, would her friend even date you? If she is a loyal friend she would never even consider it. There are a lot of girls out there, go find one that is not friends with your ex, that is just a sloppy situation.
Kinda yes. Your ex will hate you even more and will be happy that she is no longer with you. But if you don't care about that and u have something speshul going on with that girl... then I guess go for it. She can't be a true friend anyways if she gives you a green light. Heck most women make shitty friends. You do you.
If it's over, then it's over. I don't understand why people don't like it, once the relationship ends people are free to date whoever they want. I think that getting angry because of such a thing childish and it shows that the offended part didn't move on yet.