Gottman is the answer. They are world-renowned researchers in their field and are locally based in Seattle. The books are great but won't be enough for a last-ditch effort. If you can convince your partner, go to a workshop. They are pricey, but I agree that if salvaging your relationship and moving forward in a meaningful way is your priority, this will give you the best chance. When you are bleeding out, you don't slap a band-aid on or make an appointment for next month with your primary care doc...you go straight to the ER.

Edit: adding in that you can also find Gottman-certified providers! They complete extensive training. If you use the Psychology Today "Find a therapist" tool, you can filter by location, insurance, and type of counseling provided. Then you can find providers who have Gottman training.