It takes time. Don't be too hard and yourself...and vent away!
2.5 years ago I had so much hatred and it spewed into other areas of my life. I couldn't imagine ever wanting to be involved with another man, A or not.
Today I am only rarely triggered by something from the past. I have been able to open myself up to a new (healthy) relationship.
It takes time, but things will get better for you!