My ex is a dick. Plain and simple, I'm mortified I ever spoke to him, let alone married him.
Unfortunately, I did, fortunately I got a wonderful child out of it, unfortunately this means that I'm stuck having to put up with him being in my life in some way forever.
Ex has a habit of bitching about me, and trying his best to cause arguments with me over nothing.
Take him for example blowing up at me for 'making huge decisions about DD's life without consulting him, he's not just a babysitter you know' The supposed 'big decisions' were DD being ready to stop wearing nappies during the day (we've been potty training for a while and she has been using the potty/loo everytime, having no accidents during the day and is dry through the night) It wasn't really a decision, DD was just ready.
Also I have decided to put DD in nursery for an additional day a week, a day when we will both be working (he's got a new job and used to have her on this day). Not really a decision either, I can't just leave her at home on her own, she's 2.5 
He also had the nerve to tell me an extra day was too expensive when he doesn't pay anything towards nursery fees and has given me a grand total of £30 maintenance over the past 5 months.
He was a truly shite husband, he lied, cheated, secretly got us in debt, abandoned me during DD's birth and was horribly immature all round.
I hate that I waste any amount of energy on his pathetic drivel, I try very hard to maintain a civil relationship with him for DD's sake but he makes it incredibly hard with his incessant attempts to wind me up.
How would you deal with this? What can I do to honestly not give a shit?