I haven't heard of it, but I suppose it is possible. If my ex told me she's been secretly doing therapy and DBT this whole time and wanted to get back with me, I would still not trust it. I would probably try not to laugh. There is just too much water under the bridge. It isn't just about
them and if they get well. It is also about how WE feel just being around them. I don't think it would even be possible for me to feel safe with her and not have constant painful triggers, no matter how "normal" she became. It is about the damage done to us, too -not just about their almighty relative mental health

.
Incidentally, my ex did start therapy after our divorce. And within a month or two we were back together. If that happens, my advice is to not fall for it. Within a month or two after getting back together with her, she moved back in and it went back to the same way. Soon, she didn't really believe she needed help at all. "I don't even know why I'm getting therapy." And it went back to the same thing... .I was blamed for "going back to being un-confident", while she expected the entire world to revolve around her, waited like a set-trap to see if/how I would give her what she wanted, dumped everything on me, and cheated on me... .including with the 18 year old friend of our son. If she DOES get help, it will take at least a few years of committed work from her... .WITHOUT you being there to dump her emotional conflicts onto in a relationship. I suppose it happens, but the idea of my ex wife committing to
anything long-term is not realistic.
I do hope she does, still, for the sake of our kids. She would definitely be a better mother to them if she was not constantly neglecting them for her latest obsession with a new guy or some other new escape and then making excuses about it or invalidating their feelings by telling them that they are overreacting.