Genghis
Firstly, I'm pleased that you survived to tell the tale, it must have been a very scary experience.
Rather belatedly (have been away for some days) I'd like to comment about filing an airprox.
I've only filed one and that was because I didn't understand how the incident had happened - even though there was rather more separation than you experienced. (about 600m, but the other a/c was flying in the opposite direction when I was cleared to continue approach on a 2.5 mile final and we would have collided if I had n't taking avoiding action.)
In the subsequent report, a gap was found in the visibility from the a/p tower and recommendations made to deal with this.
In my case, filing an airprox was a win-win and I guess that you need to figure out what filing one would do for you - maybe give you a sense of closure, if nothing else?