This dishonesty thing is a real dealbreaker for you. Take your 24/48 hrs to reflect on what you really want. Then continue to tell him directly - but calmly so he can't accuse you of "being the reason he is dishonest" (that is such BS). Tell him once and for all you cannot live with dishonesty, especially after everything you've been put through the past year. Say it simply, calm and strong. NO decisions on whether to walk or not need to be made. What you need to know inside is that you are ok with or without him. But you must also know inside you you can't live without certain boundaries - honesty, respect for your feelings, etc.
You can do it Rabbit. Maybe write out here first what you want to say to him and we'll help you. Then - just do it.