I also had terrible experiences, left and then came back.
I waited too long to come back, which was a big mistake, but the reason I came back is that I NEVER did what Feldman did past a couple of dumb online posts during the first 6 months or so after I left. In fact, I had nothing but contempt for the couple of Feldmans I encountered (one is a Failed rather than a Feldman, vehamayvin yavin) – they just wanted to stay bitter either to avoid moving on or to get 15 minutes of fame. I just wanted to move on, although deep down I wanted to come back. What kept me from coming back earlier was that I was in a place where the community was very weak and corrupt so I had nowhere to go back to.
I remained a very proud Jew; I even “destabilized” a couple of anti-Semites and made big problems for them with creditors, authorities etc. I also never did anything particularly wild, and I avoided a situation that could have led me to marry out. (Here, too, now, I see etzba elokim because circumstances ended this situation in a very nice and peaceful way before anything could have happened). I just spent most of my time working, and managed to get my 15 minutes of fame the real way, as an expert who was quoted almost daily in business papers where I lived.
On the other hand, I will never forgive the rosho, who unfortunately is in a very high place (for now) for what he did to me. I have him in mind every time I say the word Reshoim in Ashrei; when I get the amud at Mincha I yell out that word VERY loud with him in mind. (everyone thinks I am either cursing Ahmadinejad or reminding people to finish Ashrei in time for Kaddish, but I recite shomer…yashmid out loud for another reason altogether). In fact, he suffered greatly a few months after he pulled shtick on me, and as he is approaching the age of kareis, I do not expect him to be around much longer – after he got his maka he went from being a weak man who was being used by reshoim to an out and out rosho. He saw me on the street in the US and trembled with fear; that’s my revenge and I will let Hashem do the rest and erase this cancer from our midst when He sees it fit.
And I am very careful not to accept rabbonim of the type we refer to in “ohev es hamelocho vesone rabbonus” in any way at face value again or to get too close to them. Instead, I look at them as businessmen whose services I may or may not need. Sadly, the European generation that did not mix ruchnius and gashmius is gone; yeridas hadoiros is a big issue and I know to watch out and to keep away from any communal politics.
[There is an amazing “coincidence” having to do with the number of years I was off the derech and the rosho’s first maka.]