The less income you make, the more child support he has to pay. I'd file for an increase. It goes by formula and sheer numbers, so the reason you make less wouldn't be a factor.
From now on, do pick up and drop offs of the children at the local police station. I did that, and it worked beautifully.
The rest is just awful. I wish I believe in karma, but I don't. You know how they say God loves drunks and small children? Notice how the drunk driver is often the only one in the accident that walks away from a wreck? I'm 50+, there is no karma. They never have to answer for the evil they do.
All you can do is re-group, figure something out, and never, ever, ever have anything to do with an addict or a personality disordered person or a messed up person again. They do terrible things to others.
And this is why I don't like the phrase: "Separate the addiction from the person." You can't. At least not until the person him/herself separates the addiction from their own person. And as we know 80% of the time that never happens for very long.
Living well is the best revenge. You have no choice but to start over, and it's so hard and I'm so sorry. But you have a lot of years ahead of you and you can do it.