I wish I could tell you old dog. I truly do. I'd like to know myself. I know its a gradual day by day thing and its a choice we make.
But we both know not forgiving doesn't do us any good, its conceding control of ourselves to someone else.
Best thing I've found is to find an outlet, run til you throw up kind of thing. When I didn't find a healthy outlet I kicked a wall and broke a foot (really not good)
The other thing that helps me (though it does feed other issues admitedly) is empathy. There are only two real explanations behind what she is doing (the whole situation) either 1) she is not a very nice person so why would you want that or 2) she was really hurting and depression, sadness and despair left her vulnerable and desperate. If its the second and I empathise (within myself) I find it settles a little of the anger.
Enough that I can refocus on the kind of man I want to be.
And lastly, what alternative would you prefer to friendly knowing you can't change what she does, just influence how she interacts with you?
Both mid 30s, 2 young kids BD 7sep14 XW moved on long ago, now living with OM1 D paperwork in progress