Anger is one of the stages of grief, which you are going through. It's normal to feel some anger.
I'd imagine your anger should actually lessen if you're detaching properly.
I'll admit I'm the last person here who should give you advice on managing anger. Not that I was ever abusive to the XW in any way. It was just a phase I was stuck in for far too long. Still, some things that helped with my anger were exercising, going to IC, and (my favorite) yelling when I was alone. GAL was good for keeping my mind off things, but it never really helped me address the anger.
Me-47,XW-43 S13,S16 M:18 BD:4-23-17 W filed:7-17-17 (5 months of in-house separation hell) W moved out:1-6-18 D granted:2-15-18 Decree signed:3-29-18