Think of Istikhara as a "Divine GPS" (as named for an amazing lecture on istikhara by Shaykh Abdulbary Yahya).
There is no "negative" and "positive". Trust me, I've done extensive research in this area, primarily while I was engaged. You just pray istikhara and then leave it up to Allah Subhanahu wa Ta'ala. Don't expect signs, dreams, etc. Just make whatever decision you feel most comfortable with and go with it, with the knowledge that you are being guided by Rabb al-Alameen. It's a "gps" in the sense that even if you make the wrong decision, Allah Subhanahu wa Ta'ala will guide you back to the path that's right for you.
In my case, although I really wanted to marry this brother, there was always something bothering me, literally preventing me from progressing any further. I spoke to an alim and was told how istikhara works minus all the "cultural enhancements" and realized that if I had gone through with the marriage, if it wasn't meant for me, it would end in divorce.
Also sometimes people look for indicators or signs to see what they should do. This leads to them sometimes placing emphasis on the wrong thing and thus, possibly making the wrong decision. However, in the end, if it's naseeb it'll happen nevertheless.
So perhaps, if you take the time to look inside yourself, you'll see if this has made you a better or worse person. Only you can ascertain as to whether or not your journey with your ex-husband was worth the obstacles.
Just don't make the mistake of over-complicating istikhara. It's actually very simple:
Pray and have faith. Unlike pray, have faith, start searching for signs and analyzing too much. This is actually a mistake I used to make until I opened my eyes and realized the beauty of istikhara's simplicity.
