OP,
- it can be very hard (especially when you're starting the learning curve of single parenting and trying to heal from an abusive relationship).
First off, you and your son will be so much healthier and happier now you've split from your abuser. Don't lose sight of that.
Second, you've gained inestimable amounts of freedom. When I first embarked on single parenthood, my mum (who'd split up from her first marriage - I was the child of her second, happy marriage) listed all the good bits.
Being able to say "sod it, it's a nice day," pack a bag for the park/beach/where-ever and just go, without having to fit round someone who's got other plans (other plans which may have mysteriously appeared from nowhere, just to thwart your attempt to do something enjoyable).
Knowing you only have to pick up/clean/ cook for one person - your child - not child plus bloody useless man-child.
Having your house as a calm, quiet place you can both enjoy, not somewhere you have to tread on eggshells so as not to find yourself embroiled in a row (a row he'd have said he caused, even though in fact he'd engineered the situation very carefully to be damned if you do, damned if you don't).