Hey Go, thanks for the additional information. I am certain you have been friend zoned. It seems from what you posted that you have a TON of comfort but really no attraction has been built (I can say this because this girl shares herself with you, but nothing physical has happened).
I would definitely NOT underestimate the exboyfriend that much, however I do think he is NOT THE MAIN OBSTACLE here.
Let me ask you, have you tried to escalate things? I mean you've built so much comfort that I am sure it would seem weird but have you made a move on her?
I think right now you need to trigger her jealousy. Do a search on how to get out of the Friend Zone
Personally, I think you should make this girl jealous. Go no contact with her and get out a bit and let her know you have options. This will be a good start.