Teppo: I wonder if it would be easier for you to look at her role as a mom. Has she been there for your son? is she a good mom? If the answer is anything besides: no she has been physically and emotionally violent with him that you can easily separate seeing her as your W would perhaps did some bad stuff but that role is different from her role as a mom.
I get the fear of "getting off too easy" but what is the purpose of giving her a harder time? What will YOU gain from it?
