Kathrin, Welcome to DB ... although part of me always hates saying that (none of us should be here!). It's great that you're reading DR. I also read many other books on infidelity. It helped a lot.
DB offers counseling but not couples or individual counseling. They do DB coaching. It sounds like you want a pro-marriage counselor. You're wise to think of that because some counselors are not! I can't make any recommendations, I'm not from your area. But perhaps you could ask family, friends, a pastor or people in church if you attend. If you come up empty there, do some research online. Many counselors have websites these days which give you a feel for them. I think you could probably also call to feel them out. Christian-based counseling is also an option, I'm sure they're pro-marriage.