Dear Regina,
Most people with trust issues will continually attract partners or situations that will play out that trust issue. For example, a woman who was raised by a father who openly cheated on her mother will pick men who cheat on her. The answer to how you can get past this is to start with discovering where your trust issue began. From there you move into healing the issue. I always suggest working with a mental health professional with this particular issue as it can be very difficult to do on your own.  As far as your boyfriend is concerned, forgiveness is always important whether you decide to stay with him or not. If you do not forgive him, you are actually putting yourself in a type of mental prison. Once you forgive him, however, you are setting yourself free and putting yourself in a better position to decide if you want to continue in the relationship with him.