<human>: Ok. So I have just recently ended an engagement because of terrible stuff that I found out about. (Will explain in comments if you think it'll help with advice). 
        She, lets call her K, would have been the maid of honor, and after breaking off the engagement found out why she stepped out of the role halfway through the planning. She messaged me on FB after she found out the engagement ended saying she was there if I needed to talk, or needed a friend. Well, we have gotten quite close and I have even asked her out, but she declined saying it would be awkward of her to do that because of what happened between our now ex's (My ex was hooking up with her ex while engaged). 
      Here comes the But. We have now both quit even attempting to be friendly towards my ex because of situations my ex was causing, and we have gotten rather close, gone to a few small parties, gotten lunch (K works nights 5 days a week until 3am), and upon joking about me getting her a teddy bear for V-day she seemed quite excited and even in texts she has a positive attitude, except when talking about work. Not sure if she is just being friendly, or flirting. (i'm dense with women, i don't pick up on small signs). Now, at the beginning of me being rejected after asking her out we decided to be friends, but when we hang out there is obvious sexual tension, I flirt a lot when we hang out and she seems to enjoy it and we laugh and have fun when we hang out, and I have been keeping myself from escalating because of the agreement to be only friends.
  I was thinking of giving her the teddy bear on Valentine's day with a note and an attempt to escalate the friendship into something more. Should I attempt to turn this into a dating relationship or just drop it because I think she has feelings for me as well.

Condense the text into a few key points
<bot>: Ex-fiance's, maid of honor and I have gotten close after engagement ended for bad reasons. Ex and I no longer speak nor do Ex and her ex-bf. Not sure hot to proceed.