Don’t throw in the towel until you sort through what has happened. Couples counseling right now is important. There’s a lot invested here, and it seems as if your prior history and break up is playing a part in this. You do not want to go forward in a relationship with a person you cannot trust. Yet it seems there is much working with the two of you.
Take the time to explore what is happening in couples therapy. Get a third person opinion from the therapist and bring the issue out where someone skilled can help you determined if trust can be re-established. If it can’t, then you throw in the towel and take the lessons forward. If it can, you’ll have established a better foundation on which to build. The “Find Help” tab at the top of the page can help you find someone in your area.