That kind of obsession can often be a control issue, trying to control something when you can't control other things going on around you. Trouble is it all too easily gets out of control and takes over.
Her asking for help is probably one of the best signs you could hope for and, chances are, her husband leaving might be the fresh start she needs to find her own control or learn to live with things as they are without resorting to such damaging behaviour.
I think of some of thie things I've done in the past and it horrifies me. You can't see it at the time, it's a compulsion, obsession if you like.
Getting better is a lot to do with learning to regain the control and her steps towards getting help are a huge step towards that.
Cognitive behavioural therapy has really helped me. Smashed a lot of my wrong and damaging perceptions and helping me let go and understand myself a lot better.
I paid to see someone privately as you don't get the long waiting lists and it can be arranged a lot more conveniently. It was expensive but worth it and has made a big difference.
Change doesn't happen overnight though, destructive behaviour can be very hard to change, especially the longer it has been going on.
There will still be bad days and the more open and non-judgmental you can be the better. Sometimes you have to give in a little and drop back down to come back up again, it's not necessarily a failure but a part of the process.