I'm also in a state where I'm often angry about the things I went through in my relationship: angry about things my AXW did, angry that I made classic codependent mistakes, and angry that I didn't stand my ground earlier and leave when the truly bad abuse began.
Several books that I've read in the recent past have alluded to or just straight out said that I must accept that I am free to feel whatever I'm feeling at any given time. If I'm angry, accept that I am free to be angry and it will run its course. If I'm happy, accept that I am free to be happy and don't feel guilty about it. Trying to repress my feelings will just reinforce them and give them greater power over me.
To quote Alan Watts, "We cannot exterminate our own evils any more than the Earth can throw out its weeds. But weeds have not choked all those parts of the Earth where nature has been left to her own devices; it is only when man interferes with nature that he begins to notice the inconvenient persistence of certain lowly plants to which he gives the name of weeds. Yet even the best regulated gardens have to have their soil filled with manure and other 'unpleasant' fertilizers, and what is true of the soil is also true of the human mind. Where the roses of virtue bloom in their glory there will certainly be a bed of manure; it will be kept in its place, to be sure, but it will certainly be there. This is not said in cynicism, because the 'filthiness' of the soil in no way detracts from the beauty of the flower except in the imaginations of those who would like to see roses blooming in mid-air, whose oversensitive tastes are revolted by the realities of nature. However, the expert and enthusiastic gardener finds something almost pleasurable in manure; certainly he does not smear it all over the plants, but a soil well mixed with it he calls 'good' and 'rich' - not 'foul' and 'putrid.'"