Forgiveness is hard for me. Is it all right to start and stop the process of forgiveness?

Yes, it is all right to start and stop the forgiveness process if you feel that you need a rest from the challenges of forgiving.  As an analogy, if we want to be physically fit, we do not work at that fitness 10 hours a day every day.  We need to be more temperate than that.  So, working on forgiveness for an hour or less some of the days of a week seems reasonable to me.  Taking a week off is fine.  I was asked by a person if she could take a year off of the forgiveness process.  This, to me, would be similar to taking off a year of physical fitness training.  One likely would get out of shape waiting that long.  One probably would get out of forgiveness-fitness shape as well waiting for a year.

For additional information, see The Four Phases of Forgiveness.