I'm so sorry OWW not much advice really, apart from maybe give Indie a chance. I know it's so easy when feeling crap to want to throw everything away, even the good, and hibernate for a while. But you know what works for you.
And Titto can waltz off into someone else's arms because he can play at being fancy free, whereas you have all the grown up stuff to handle with the kids and real life. Does new wife even know what he's left behind? It's more than likely she's fallen for his facade not the scumbag beneath. 
Good news about your mum 48. I think this thread needs our own Faceless Men, a la Game of Thrones, to deal with the likes of your sister and all the OD fuckwits 
So are things still on with R&R after your talk?